Cooling strategy for battery systems

ABSTRACT

Embodiments describe a battery system that includes a first battery module coupled to a regenerative braking system and a control module that controls operation of the battery system by: determining a predicted driving pattern over a prediction horizon using a driving pattern recognition model based in part on a battery current and a previous driving pattern; determining a predicted battery resistance of the first battery module over the prediction horizon using a recursive battery model based in part on the predicted driving pattern, the battery current, a present bus voltage, and a previous bus voltage; determining a target trajectory of a battery temperature of the first battery module over a control horizon using an objective function; and controlling magnitude and duration of electrical power supplied from the regenerative such that a predicted trajectory of the battery temperature is guided toward the target trajectory of the battery temperature during the control horizon.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/788,223 filed Jun. 30, 2015, now U.S. Pat. No. 10,099,562, whichclaims priority to and benefit of U.S. Provisional Application No.62/064,318 filed Oct. 15, 2014 and U.S. Provisional Application No.62/075,140 filed Nov. 4, 2014, each of which is hereby incorporatedherein by reference in its entirety for all purposes.

BACKGROUND

The present disclosure relates generally to the field of batteries andbattery systems. More specifically, the present disclosure relates tomanagement of operational parameters in a lithium ion battery.

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present disclosure,which are described below. This discussion is believed to be helpful inproviding the reader with background information to facilitate a betterunderstanding of the various aspects of the present disclosure.Accordingly, it should be understood that these statements are to beread in this light, and not as admissions of prior art.

An automotive vehicle that uses one or more battery systems forproviding all or a portion of the motive power for the vehicle can bereferred to as an xEV, where the term “xEV” is defined herein to includeall of the following vehicles, or any variations or combinationsthereof, that use electric power for all or a portion of their vehicularmotive force. For example, xEVs include electric vehicles (EVs) thatutilize electric power for all motive force. As will be appreciated bythose skilled in the art, hybrid electric vehicles (HEVs), alsoconsidered xEVs, combine an internal combustion engine propulsion systemand a battery-powered electric propulsion system, such as 48 Volt (V) or130V systems.

The term HEV may include any variation of a hybrid electric vehicle. Forexample, full hybrid systems (FHEVs) may provide motive and otherelectrical power to the vehicle using one or more electric motors, usingonly an internal combustion engine, or using both. In contrast, mildhybrid systems (MHEVs) may disable the internal combustion engine whenthe vehicle is idling and utilize a battery system to continue poweringthe air conditioning unit, radio, or other electronics, as well as torestart the engine when propulsion is desired. The mild hybrid systemmay also apply some level of power assist, during acceleration forexample, to supplement the internal combustion engine.

Further, a micro-hybrid electric vehicle (mHEV) also uses a “Stop-Start”system similar to the mild hybrids, but the micro-hybrid systems of amHEV may or may not supply power assist to the internal combustionengine and operates at a voltage below 60V. For the purposes of thepresent discussion, it should be noted that mHEVs may not technicallyuse electric power provided directly to the crankshaft or transmissionfor any portion of the motive force of the vehicle, but an mHEV maystill be considered as an xEV since it does use electric power tosupplement a vehicle's power needs when the vehicle is idling withinternal combustion engine disabled.

In addition, a plug-in electric vehicle (PEV) is any vehicle that can becharged from an external source of electricity, such as wall sockets,and the energy stored in the rechargeable battery packs drives orcontributes to drive the wheels. PEVs are a subcategory of EVs thatinclude all-electric or battery electric vehicles (BEVs), plug-in hybridelectric vehicles (PHEVs), and electric vehicle conversions of hybridelectric vehicles and conventional internal combustion engine vehicles.

xEVs as described above may provide a number of advantages as comparedto more traditional gas-powered vehicles using only internal combustionengines and traditional electrical systems, which are typically 12Vsystems powered by a lead-acid battery. In fact, xEVs may produce fewerundesirable emission products and may exhibit greater fuel efficiency ascompared to traditional internal combustion vehicles. For example, somexEVs may utilize regenerative braking to generate and store electricalenergy as the xEV decelerates or coasts. More specifically, as the xEVreduces in speed, a regenerative braking system may convert mechanicalenergy into electrical energy, which may then be stored and/or used topower to the xEV.

Often, a lithium ion battery may be used to facilitate efficientlycapturing the generated electrical energy. More specifically, thelithium ion battery may capture/store electrical energy duringregenerative braking and subsequently supply electrical power to thevehicle's electrical system. However, as the lithium ion batteryoperates, operational parameters of the lithium ion battery may change.For example, the temperature of the lithium ion battery may increaseover operation of the vehicle. It is now recognized that temperature ofa lithium ion battery may affect performance and/or life span of thebattery. For example, temperature increases may decrease life span ofthe battery, decrease fuel economy contribution of the battery, placethe battery in an undesired operating range, or any combination thereof.

SUMMARY

Certain embodiments commensurate in scope with the disclosed subjectmatter are summarized below. These embodiments are not intended to limitthe scope of the disclosure, but rather these embodiments are intendedonly to provide a brief summary of certain disclosed embodiments.Indeed, the present disclosure may encompass a variety of forms that maybe similar to or different from the embodiments set forth below.

Accordingly, a first embodiment describes a battery system used in anautomotive vehicle. The battery system includes a first battery modulecoupled to a regenerative braking system. The battery system alsoincludes a control module that controls operation of the battery systemby: determining a predicted driving pattern of the automotive vehicleover a prediction horizon using a driving pattern recognition modelbased at least in part on a battery current and a previous drivingpattern of the automotive vehicle; determining a predicted batteryresistance of the first battery module over the prediction horizon usinga recursive battery model based at least in part on the predicteddriving pattern, the battery current, a present bus voltage, and aprevious bus voltage; determining a target trajectory of a batterytemperature of the first battery module over a control horizon using anobjective function to balance effects of the battery temperature onaspects of the first battery module; and controlling magnitude andduration of electrical power supplied from the regenerative brakingsystem to the first battery module such that a predicted trajectory ofthe battery temperature is guided toward the target trajectory of thebattery temperature during the control horizon.

Additionally, a second embodiment describes a tangible non-transitory,computer readable medium of a lithium ion battery system that storesinstructions executable by a processor in an automotive vehicle. Theinstructions include instructions to determine, using the processor,temperature of a lithium ion battery module; determine, using theprocessor, a temperature threshold; instruct, using the processor, anelectrical energy generator to output a high electrical power when thetemperature of the lithium ion battery module is not greater than thetemperature threshold to enable the lithium ion battery system toutilize a first amount of storage capacity to capture generatedelectrical energy; and instruct, using the processor, the electricalenergy generator to output a low electrical power when the temperatureof the lithium ion battery module is greater than the temperaturethreshold to enable the lithium ion battery system to utilize a secondamount of storage capacity to capture generated electrical energy, inwhich the second amount is less than the first amount.

Furthermore, a third embodiment describes a method for controllingtemperature of a battery system. The method includes determining, usinga control module, temperature of a lithium ion battery module in thebattery system; determining, using the control module, a temperaturethreshold and a target trajectory of the temperature over a controlhorizon; determining, using the control module, battery parametersetpoints based at least in part on a thermal predictive model, in whichthe thermal predictive model is configured to describe a relationshipbetween the battery parameter setpoints and a predicted trajectory ofthe temperature over a prediction horizon; and controlling, using thecontrol module, operation of the battery system to implement the batteryparameter setpoints such that the predicted trajectory of thetemperature is guided toward the target trajectory and maintained belowthe temperature threshold over the control horizon.

DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a perspective view of a vehicle, in accordance with anembodiment;

FIG. 2 is a schematic view of a battery system in the vehicle of FIG. 1,in accordance with an embodiment;

FIG. 3 is a schematic diagram of a passive architecture for the batterysystem of FIG. 2, in accordance with an embodiment;

FIG. 4 is a schematic diagram of a semi-passive architecture for thebattery system of FIG. 2, in accordance with an embodiment;

FIG. 5 is a graph describing voltage characteristics of a lithium ionbattery and a lead-acid battery used in the battery system of FIG. 2, inaccordance with an embodiment;

FIG. 6 is a schematic diagram of the lithium ion battery, in accordancewith an embodiment;

FIG. 7A is a perspective view of a lithium ion battery, in accordancewith an embodiment;

FIG. 7B is an exploded view of the lithium ion battery of FIG. 7A, inaccordance with an embodiment;

FIG. 8 is a block diagram of a control module used to in a reactivecontrol scheme on the battery system of FIG. 2, in accordance with anembodiment;

FIG. 9 is a flow diagram describing a first process for reactive controlof the battery system of FIG. 2 using the control module of FIG. 8, inaccordance with an embodiment;

FIG. 10 is a flow diagram describing a second process for reactivecontrol of the battery system of FIG. 2 using the control module of FIG.8, in accordance with an embodiment;

FIG. 11 is a plot describing internal resistance of a lithium ionbattery over its lifetime when the lithium ion battery is operated at afirst location, in accordance with an embodiment;

FIG. 12 is a plot describing temperature of the lithium ion battery whenoperated in a first scenario at the first location, in accordance withan embodiment;

FIG. 13 is a plot describing temperature of the lithium ion battery whenoperated in a second scenario at the first location, in accordance withan embodiment;

FIG. 14 is plot describing internal resistance of a lithium ion batteryover its lifetime when the lithium ion battery is operated at a secondlocation, in accordance with an embodiment;

FIG. 15 is a plot describing temperature of the lithium ion battery whenoperated in a third scenario at the second location, in accordance withan embodiment;

FIG. 16 is a plot describing temperature of the lithium ion battery whenoperated in a fourth scenario at the second location, in accordance withan embodiment;

FIG. 17A is a plot describing temperature of a lithium ion battery whenoperated in a fifth scenario, in accordance with an embodiment;

FIG. 17B is a plot describing regenerative efficiency and regenerativethroughput when operated in the fifth scenario, in accordance with anembodiment;

FIG. 17C is a plot describing charge and discharge currents whenoperated in the fifth scenario, in accordance with an embodiment;

FIG. 18 is a block diagram of a control module used in an intelligentcontrol scheme on the battery system of FIG. 2, in accordance with anembodiment;

FIG. 19 is a flow diagram describing a process for intelligent controlof the battery system of FIG. 2 using the control module of FIG. 18, inaccordance with an embodiment;

FIG. 20 is block diagram of a thermal predictive model used in thecontrol module of FIG. 18, in accordance with an embodiment;

FIG. 21 is a flow diagram describing a process for determining batteryparameter setpoints using the thermal predictive model of FIG. 20, inaccordance with an embodiment;

FIG. 22 is a block diagram of a driving pattern recognition model usedin the control module of FIG. 18, in accordance with an embodiment;

FIG. 23 is a flow diagram describing a process for determining predictedvehicle drive pattern using the driving pattern recognition model ofFIG. 22, in accordance with an embodiment;

FIG. 24 is a block diagram of a recursive battery model used in thecontrol module of FIG. 18, in accordance with an embodiment;

FIG. 25 is a flow diagram describing a process for determining batterystate of health using the recursive battery model of FIG. 24, inaccordance with an embodiment;

FIG. 26 is a block diagram of a battery life model used in the controlmodule of FIG. 18, in accordance with an embodiment;

FIG. 27 is a flow diagram describing a process for determining apredicted battery life span using the battery life model of FIG. 26, inaccordance with an embodiment;

FIG. 28 is a flow diagram describing a process for determining a currentbattery age using the recursive battery model of FIG. 24, in accordancewith an embodiment;

FIG. 29 is a block diagram of a fuel economy model used in the controlmodule of FIG. 18, in accordance with an embodiment;

FIG. 30 is a flow diagram describing a process for determining a targettemperature trajectory using the fuel economy model of FIG. 29, inaccordance with an embodiment;

FIG. 31A is a plot describing a hypothetical driving pattern, inaccordance with an embodiment; and

FIG. 31B is a plot describing charge and discharge currents of a lithiumion battery during the hypothetical driving pattern of FIG. 31A, inaccordance with an embodiment.

DETAILED DESCRIPTION

One or more specific embodiments of the present techniques will bedescribed below. In an effort to provide a concise description of theseembodiments, not all features of an actual implementation are describedin the specification. It should be appreciated that in the developmentof any such actual implementation, as in any engineering or designproject, numerous implementation-specific decisions must be made toachieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which may vary from oneimplementation to another. Moreover, it should be appreciated that sucha development effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure.

The battery systems described herein may be used to provide power tovarious types of electric vehicles (xEVs) and other high voltage energystorage/expending applications (e.g., electrical grid power storagesystems). For example, xEVs may include regenerative braking systems tocapture and store electrical energy generated when the vehicle isdecelerating or coasting. The captured electrical energy may then beutilized to supply power to the vehicle's electrical system. As anotherexample, battery modules in accordance with present embodiments may beincorporated with or provide power to stationary power systems (e.g.,non-automotive systems).

In some embodiments, the battery system may include a lithium ionbattery coupled in parallel with one or more other batteries, such as alead-acid battery, to capture generated electrical energy and supplyelectrical power to electrical devices. In some embodiments, electricalenergy may be generated by a regenerative braking system that convertsmechanical energy into electrical energy. The lithium ion battery maythen be used to capture and store the electrical energy generated duringregenerative braking. Subsequently, the lithium ion battery may supplyelectrical power to a vehicle's electrical system.

Based on the advantages over traditional gas-power vehicles,manufacturers that generally produce traditional gas-powered vehiclesmay desire to utilize improved vehicle technologies (e.g., regenerativebraking technology) within their vehicle lines. Often, thesemanufacturers may utilize one of their traditional vehicle platforms asa starting point. Accordingly, since traditional gas-powered vehiclesare designed to utilize 12 volt battery systems, a 12 volt lithium ionbattery may be used to supplement a 12 volt lead-acid battery. Morespecifically, the 12 volt lithium ion battery may be used to moreefficiently capture electrical energy generated during regenerativebraking and subsequently supply electrical energy to power the vehicle'selectrical system. Additionally, in a mHEV, the internal combustionengine may be disabled when the vehicle is idle. Accordingly, the 12volt lithium ion battery may be used to crank (e.g., restart) theinternal combustion engine when propulsion is desired.

However, as advancements are made in vehicle technologies, high voltageelectrical devices may be included in the vehicle's electrical system.For example, the lithium ion battery may supply electrical energy to anelectric motor in a FHEV. Often, these high voltage electrical devicesutilize voltages greater than 12 volts, for example, up to 48, 96, or130 volts. Accordingly, in some embodiments, the output voltage of a 12volt lithium ion battery may be boosted using a DC-DC converter tosupply power to the high voltage devices. Additionally or alternatively,a 48 volt lithium ion battery may be used to supplement a 12 voltlead-acid battery. More specifically, the 48 volt lithium ion batterymay be used to more efficiently capture electrical energy generatedduring regenerative braking and subsequently supply electrical energy topower the high voltage devices.

Thus, the design choice regarding whether to utilize a 12 volt lithiumion battery or a 48 volt lithium ion battery may depend directly on theelectrical devices included in a particular vehicle. Although thevoltage characteristics may differ, the operational principles of a 12volt lithium ion battery and a 48 volt lithium ion battery are generallysimilar. More specifically, as described above, both may be used tocapture electrical energy during regenerative braking and subsequentlysupply electrical power to electrical devices in the vehicle.Additionally, as both operate over a period of time, the operationalparameters may change. For example, the temperature of the lithium ionbattery may increase the longer the lithium ion battery is in operation.

Accordingly, to simplify the following discussion, the presenttechniques will be described in relation to a battery system with a 12volt lithium ion battery and a 12 volt lead-acid battery. However, oneof ordinary skill in art should be able to adapt the present techniquesto other battery systems, such as a battery system with a 48 voltlithium ion battery and a 12 volt lead-acid battery.

As described above, the operational parameters of a lithium ion batterymay change over operation of the vehicle. For example, the temperatureof the lithium ion battery may gradually increase during operation. Morespecifically, charging and/or discharging the lithium ion battery maygenerate heat. As such, repeatedly charging and discharging the lithiumion battery may increase the temperature of the lithium ion battery.Generally, a lithium ion battery may be designed to function over a widerange of operating temperatures. However, when the temperature reachesan upper threshold (e.g., 70° Celsius) or increases at a fast rate, theperformance and/or life span of the lithium ion battery may be affected.For example, increased battery temperature may reduce energy captureefficiency of the lithium ion battery and/or increase internalresistance a faster rate, which may shorten lifespan of the lithium ionbattery.

Accordingly, the present disclosure describes techniques to facilitatecontrolling operational parameters of the lithium ion battery. Forexample, as will be described in more detail below, a control module mayinstruct the battery system to implement battery parameter setpoints tode-rate and/or re-rate the battery system. In some embodiments, thebattery parameter setpoints may include charging power (e.g., current orvoltage) setpoints, discharging power setpoints, or any combinationthereof. More specifically, the battery system may be de-rated to reducethe operation of the lithium ion battery (e.g., number of charge anddischarge cycles). In this manner, the heat caused bycharging/discharging may be reduced, which may facilitate cooling thelithium ion battery. Once the lithium ion battery has been sufficientlycooled, the battery system may be re-rated to resume normal operation ofthe lithium ion battery. In other words, the lithium ion battery mayincrease the amount of charging and/or discharging performed.

Additionally, as will be described in more detail below, the presentdisclosure provides techniques for both reactive and intelligent (e.g.,predictive) control schemes of lithium ion battery temperature. Forexample, in a reactive control scheme, a control module may de-rate thebattery system when temperature of the lithium ion battery reaches atemperature threshold or increases faster than a threshold rate, therebyreducing operation of the lithium ion battery. Once the temperature ofthe lithium ion battery falls below a temperature threshold, the controlmodule may re-rate the battery system, thereby resuming maximumoperation of the lithium ion battery. In other words, in a reactivescheme, the control module may de-rate and re-rate the battery systembased on a current temperature of the lithium ion battery.

On the other hand, in an intelligent control scheme, a control modulemay de-rate and re-rate the battery system based at least in part on apredicted trajectory of lithium ion battery temperature, for example,determined via a thermal predictive model. In some embodiments, thecontrol module may de-rate the battery system when the predictedtrajectory of lithium ion battery temperature is expected to reach atemperature threshold or is expected to increase faster than a thresholdrate, thereby decreasing magnitude of the future lithium ion batterytemperature. Once the predicted trajectory of lithium ion batterytemperature falls below a temperature threshold, the control module mayre-rate the battery system.

Thus, embodiments of the techniques described herein enable operationalparameters of the lithium ion battery, such as temperature, amount ofstored energy, and/or duration of operation, to be controlled to improveperformance (e.g., energy capture efficiency) and/or life span of thebattery system. For example, as will be described in more detail below,de-rating and re-rating the battery system may supplement a coolingsystem, such as cooling fins. In fact, in some embodiments, de-ratingand re-rating techniques may enable the battery system to rely solely onpassive cooling features, which may reduce bulkiness of the batterysystem as well as manufacturing complexity and cost of the batterysystem.

To help illustrate, FIG. 1 is a perspective view of an embodiment of avehicle 10, which may utilize a regenerative braking system. Althoughthe following discussion is presented in relation to vehicles withregenerative braking systems, the techniques described herein areadaptable to other vehicles that capture/store electrical energy with abattery, which may include electric-powered and gas-powered vehicles.

As discussed above, it would be desirable for a battery system 12 to belargely compatible with traditional vehicle designs. Accordingly, thebattery system 12 may be placed in a location in the vehicle 10 thatwould have housed a traditional battery system. For example, asillustrated, the vehicle 10 may include the battery system 12 positionedsimilarly to a lead-acid battery of a typical combustion-engine vehicle(e.g., under the hood of the vehicle 10). Furthermore, as will bedescribed in more detail below, the battery system 12 may be positionedto facilitate managing temperature of the battery system 12. Forexample, in some embodiments, positioning a battery system 12 under thehood of the vehicle 10 may enable an air duct to channel airflow overthe battery system 12 and cool the battery system 12.

A more detailed view of the battery system 12 is described in FIG. 2. Asdepicted, the battery system 12 includes an energy storage component 14coupled to an ignition system 16, an alternator 18, a vehicle console20, and optionally to an electric motor 22. Generally, the energystorage component 14 may capture/store electrical energy generated inthe vehicle 10 and output electrical energy to power electrical devicesin the vehicle 10.

In other words, the battery system 12 may supply power to components ofthe vehicle's electrical system, which may include radiator coolingfans, climate control systems, electric power steering systems, activesuspension systems, auto park systems, electric oil pumps, electricsuper/turbochargers, electric water pumps, heated windscreen/defrosters,window lift motors, vanity lights, tire pressure monitoring systems,sunroof motor controls, power seats, alarm systems, infotainmentsystems, navigation features, lane departure warning systems, electricparking brakes, external lights, or any combination thereof.Illustratively, in the depicted embodiment, the energy storage component14 supplies power to the vehicle console 20 and the ignition system 16,which may be used to start (e.g., crank) the internal combustion engine24.

Additionally, the energy storage component 14 may capture electricalenergy generated by the alternator 18 and/or the electric motor 22. Insome embodiments, the alternator 18 may generate electrical energy whilethe internal combustion engine 24 is running. More specifically, thealternator 18 may convert the mechanical energy produced by the rotationof the internal combustion engine 24 into electrical energy.Additionally or alternatively, when the vehicle 10 includes an electricmotor 22, the electric motor 22 may generate electrical energy byconverting mechanical energy produced by the movement of the vehicle 10(e.g., rotation of the wheels) into electrical energy. Thus, in someembodiments, the energy storage component 14 may capture electricalenergy generated by the alternator 18 and/or the electric motor 22during regenerative braking. As such, the alternator 18 and/or theelectric motor 22 are generally referred to herein as electrical energygenerators.

To facilitate capturing and supplying electric energy, the energystorage component 14 may be electrically coupled to the vehicle'selectric system via a bus 26. For example, the bus 26 may enable theenergy storage component 14 to receive electrical energy generated bythe alternator 18 and/or the electric motor 22. Additionally, the bus 26may enable the energy storage component 14 to output electrical power tothe ignition system 16 and/or the vehicle console 20. Accordingly, whena 12 volt battery system 12 is used, the bus 26 may carry electricalpower typically between 8-18 volts.

Additionally, as depicted, the energy storage component 14 may includemultiple battery modules. For example, in the depicted embodiment, theenergy storage component 14 includes a lithium ion (e.g., a first)battery module 28 and a lead-acid (e.g., a second) battery module 30,which each includes one or more battery cells. In other embodiments, theenergy storage component 14 may include any number of battery modules.Additionally, although the lithium ion battery module 28 and lead-acidbattery module 30 are depicted adjacent to one another, they may bepositioned in different areas around the vehicle. For example, thelead-acid battery module 30 may be positioned in or about the interiorof the vehicle 10 while the lithium ion battery module 28 may bepositioned under the hood of the vehicle 10.

In some embodiments, the energy storage component 14 may includemultiple battery modules to utilize multiple different batterychemistries. For example, the lithium ion battery module 28 may improveperformance of the battery system 12 since a lithium ion batterychemistry generally has a higher coulombic efficiency and/or a higherpower charge acceptance rate (e.g., higher maximum charge current orcharge voltage) than a lead-acid battery chemistry. As such, thecapture, storage, and/or distribution efficiency of the battery system12 may be improved.

To facilitate controlling the capturing and storing of electricalenergy, the battery system 12 may additionally include a control module32. More specifically, the control module 32 may control operations ofcomponents in the battery system 12, such as relays (e.g., switches)within energy storage component 14, the alternator 18, and/or theelectric motor 22. For example, the control module 32 may regulateamount of electrical energy captured/supplied by each battery module 28or 30 (e.g., to de-rate and re-rate the battery system 12), perform loadbalancing between the battery modules 28 and 30, determine a state ofcharge of each battery module 28 or 30, determine temperature of eachbattery module 28 or 30, determine a predicted temperature trajectory ofeither battery module 28 and 30, determine predicted life span of eitherbattery module 28 or 30, determine fuel economy contribution by eitherbattery module 28 or 30, control magnitude of voltage or current outputby the alternator 18 and/or the electric motor 22, and the like.

Accordingly, the control module (e.g., unit) 32 may include one orprocessor 34 and one or more memory 36. More specifically, the one ormore processor 34 may include one or more application specificintegrated circuits (ASICs), one or more field programmable gate arrays(FPGAs), one or more general purpose processors, or any combinationthereof. Additionally, the one or more memory 36 may include volatilememory, such as random access memory (RAM), and/or non-volatile memory,such as read-only memory (ROM), optical drives, hard disc drives, orsolid-state drives. In some embodiments, the control module 32 mayinclude portions of a vehicle control unit (VCU) and/or a separatebattery control module.

Furthermore, as depicted, the lithium ion battery module 28 and thelead-acid battery module 30 are connected in parallel across theirterminals. In other words, the lithium ion battery module 28 and thelead-acid battery module 30 may be coupled in parallel to the vehicle'selectrical system via the bus 26. To help illustrate, embodiments of thelithium ion module 28 and the lead-acid battery module 30 coupled inparallel are described in FIGS. 3 and 4.

More specifically, FIG. 3 describes the lithium ion battery module 28and the lead-acid battery module 30 in a passive parallel architecturebattery system 38A and FIG. 4 describes the lithium ion battery module28 and the lead-acid battery module 30 in a semi-passive parallelarchitecture battery system 38B. As depicted, in both architectures thelead-acid battery module 30 and the lithium ion battery module 28 arecoupled in parallel with the ignition system 16, an electrical energygenerator 42 (e.g., the electric motor 22 and/or alternator 18), and thevehicle's electrical system 44 via the bus 26. However, in thesemi-passive battery system 38B the lithium ion battery module 28 may beselectively coupled to the bus 26 via a relay 46 (e.g., switch) inseries with the lithium ion battery 28 while, in the passive batterysystem 38A, the lead-acid battery module 30 and the lithium ion batterymodule 28 are both directly coupled to the bus 26.

Accordingly, in the passive battery system 38A, the operation of thebattery module 30 and the lithium ion battery module 28 may be based atleast in part on characteristics of each of the batteries. Morespecifically, the charging of the batteries 28 and 30 may be controlledby characteristics of the lithium ion battery module 28 and thelead-acid battery module 30 and/or the power (e.g., voltage or current)output by the electrical energy generator 42. For example, when thelead-acid battery module 30 is fully charged or close to fully charged(e.g., generally full state of charge), the lead-acid battery module 30may have a high internal resistance that steers current toward thelithium ion battery module 28. Additionally, when the open-circuitvoltage of the lithium ion battery module 28 is higher than the voltageoutput by the electrical energy generator 42, the lithium ion batterymodule 28 may cease capturing additional electrical energy.

Similarly, the discharging of the batteries 28 and 30 may also be basedat least in part on characteristics of the lithium ion battery module 28and the lead-acid battery module 30. For example, when the open-circuitvoltage of the lithium ion battery module 28 is higher than theopen-circuit voltage of the lead-acid battery module 30, the lithium ionbattery module 28 may provide power by itself, for example to theelectrical system 44, until it nears the open-circuit voltage of thelead-acid battery module 30.

As can be appreciated, the characteristics of the lithium ion batterymodule 28 may vary when different configurations (e.g., chemistries) areused. In some embodiments, the lithium ion battery module 28 may be alithium nickel manganese cobalt oxide (NMC) battery, a lithium nickelmanganese cobalt oxide/lithium-titanate (NMC/LTO) battery, a lithiummanganese oxide/lithium-titanate (LMO/LTO) battery, a nickel-metalhydride (NiMH) battery, a nickel-zinc (NiZn) battery, a lithium ironphosphate (LFP) battery, or the like. More specifically, an NMC batterymay utilize battery cells 56 having a lithium nickel manganese cobaltoxide cathode with a graphite anode, an NMC/LTO battery may utilizebattery cells having a lithium manganese oxide cathode with alithium-titanate anode, an LMO/LTO battery may utilize battery cellshaving a lithium manganese oxide cathode and a lithium-titanate anode,and an LFP battery may utilize battery cells having a lithium ironphosphate cathode and a graphite anode.

The battery chemistries utilized in the lithium ion battery module 28may be selected based on desired characteristics, such as coulombicefficiency, charge acceptance rate, power density, and voltage overlapwith the lead-acid battery. For example, the NMC/LTO battery chemistrymay be selected due to its high specific power at 50% state of charge(e.g., 3700 W/kg) and/or due to its high discharge current (e.g., 350A),which may enable the lithium ion battery module 28 to supply a greateramount of electrical power, for example, to power a high voltage device.

Although the techniques described herein may be adapted to a number ofdifferent battery chemistries, to simplify the following discussion, thelithium ion battery module 28 will be described as an NMC/LTO battery.To help illustrate the operation (e.g., charging/discharging) of thebatteries 28 and 30, the voltage characteristics of the lithium ionbattery module 28 and the lead-acid battery module 30 in a 12 voltbattery system 12 are described in FIG. 5. It should be appreciated thatthe voltage characteristics described in FIG. 5 are merely intended tobe illustrative and not limiting.

More specifically, FIG. 5 is a plot that describes the open-circuitvoltage of the lithium ion battery module 28 with a NMC/LTO voltagecurve 48 and the open-circuit voltage of the lead-acid battery module 30with a PbA voltage curve 50 over the batteries' total state of chargeranges (e.g., from 0% state of charge to 100% state of charge), in whichstate of charge is shown on the X-axis and voltage is shown on theY-axis. As described by the NMC/LTO voltage curve 48, the open-circuitvoltage of the lithium ion battery module 28 may range from 12 voltswhen it is at 0% state of charge to 16.2 volts when it is at 100% stateof charge. Additionally, as described by the PbA voltage curve 50, theopen-circuit voltage of the lead-acid battery module 30 may range from11.2 volts when it is at 0% state of charge to 12.9 volts when it is at100% state of charge.

As such, the lithium ion battery module 28 and the lead-acid batterymodule 30 may be partial voltage matched because the NMC/LTO voltagecurve 48 and the lead-acid voltage curve 50 partially overlap. In otherwords, depending on their respective states of charge, the open-circuitvoltage of the lead-acid battery module 30 and lithium ion batterymodule 28 may be the same. In the depicted embodiment, the lead-acidbattery module 30 and the lithium ion battery module 28 may be atapproximately the same open-circuit voltage when they are both between12-12.9 volts. For example, when the lithium ion battery module 28 is at25% state of charge and the lead-acid battery module 30 is at a 100%state of charge, both will have an open-circuit voltage of approximately12.9 volts. Additionally, when the lithium ion battery is at 15% stateof charge and the lead-acid battery is at 85% state of charge, both willhave an open-circuit voltage of approximately 12.7 volts.

Thus, returning to FIG. 3, the operation of the electrical energygenerator 42 may be used to control operation of the battery system 12.For example, when the electrical energy generator 42 has a variableoutput voltage, the voltage characteristics of the batteries 28 and 30and/or the voltage output by the electrical energy generator 42 may beused to control operation of the battery system 12. More specifically,when the voltage output by the electrical energy generator 42 isvariable (e.g., a range of output voltages between 8-18 volts), theamount of charging/discharging performed and the amount of energy storedin the lithium ion battery module 28 may be controlled by determining aspecific voltage to be output by the electrical energy generator 42. Forexample, when the electrical energy generator 42 outputs a voltagegreater than or equal to 16.2 volts, both the lithium ion battery module28 and the lead-acid battery module 30 may both utilize their fullstorage capacity (e.g., first amount of storage capacity up 100% stateof charge) to capture generated electrical energy.

However, as described above, the amount of charging/dischargingperformed by the lithium ion battery module 28 may increase thetemperature of the lithium ion battery module 28 over time. As such, thetemperature of the lithium ion battery module 28 may be regulated byde-rating the battery system 12. More specifically, as will be describedin more detail below, the battery system 12 may be de-rated by limitingthe amount of charging/discharging performed by the lithium ion batterymodule 28.

For example, the voltage output by the electrical energy generator 42may be reduced to 12.9 volts so that the lithium ion battery module 28is limited to capturing electrical energy up to 25% state of charge(e.g., second amount of storage capacity). The voltage output by theelectrical energy generator 42 may further be reduced to 12.7 volts sothat the lithium ion battery module 28 is limited to capturingelectrical energy up to 15% state of charge (e.g., second amount ofstorage capacity) and the lead-acid battery module 30 is limited tocapturing electrical energy up to 85% state of charge. In this manner,since the maximum state of charge of the lithium ion battery module 28may be reduced, the amount of charging/discharging performed by thelithium ion battery module 28 may also be reduced. As such, controllingthe voltage output by the electrical energy generator 42 may enablede-rating the battery system 12.

In addition to the output voltage, other operational characteristics ofthe electrical energy generator 42 may also be used to control operationof the battery system 12. In some embodiments, electrical energygenerator 42 has a fixed output voltage (e.g., 13.3 volts) or an outputvoltage with a small window of variation (e.g., between 13-13.3 volts).In such embodiments, the electrical energy generator 42 may controloperation of the battery system 12 by controlling magnitude of thecurrent generated and/or the duration electrical energy is beinggenerated.

For example, when the electrical energy generator 42 outputs 12.9 voltsat 200 amps and the batteries are connected in parallel, the lithium ionbattery module 28 may capture regenerative energy up to 25% state ofcharge and the lead-acid battery module 30 may capture regenerativeenergy up to 100% state of charge. Accordingly, to de-rate the batterysystem 12, the electrical energy generator 42 may maintain the lead-acidbattery module 30 and the lithium ion battery module 28 at a lower(e.g., target) state of charge, which may reduce the amount ofcharging/discharging performed by the lithium ion battery module 28since less energy is stored in the batteries 28 and 30. For example, theelectrical energy generator 42 may reduce the output current to 150 ampsso that the lithium ion battery module 28 may only be charged to 15%state of charge and the lead-acid battery module 30 may only be chargedto 85% state of charge. Additionally or alternatively, the electricalenergy generator 42 may cease generating electrical energy once thebatteries 28 and 30 reach their target states of charge.

Additionally, in some embodiments, the relay 46 may also be used tocontrol operation of the battery system 12, for example, in thesemi-passive battery system 38B of FIG. 4. More specifically, thedescribed relay 46 may be a bi-stable relay. For example, the relay 46may include a first state to connect the lithium ion battery module 28in parallel with the lead-acid battery module 30. As such, in the firststate, the semi-passive battery system 38B may operate generally thesame as the passive battery system 38A. For example, when the relay 46is in the first state and the electrical energy generator 42 has avariable output voltage, battery system 12 may be de-rated bycontrolling the voltage output by the electrical energy generator 42.

Additionally, the relay 46 may include a second state to electricallydisconnect the lithium ion battery module 28. More specifically, whenthe lithium ion battery module 28 is disconnected, it may ceasecharging/discharging and maintain its state of charge. As such,disconnecting the lithium ion battery module 28 may enable de-rating thebattery system 12 to regulate temperature of the lithium ion batterymodule 28. However, disconnecting the lithium ion battery module 28 maybe a dramatic step to take because the lead-acid battery module 30 maybe used to supply power to a larger load (e.g., more electricaldevices). In some embodiments, this may have an effect on the vehicleperformance, such as fuel economy. As such, in some embodiments,disconnecting the lithium ion battery module 28 may be a last resort toregulate temperature of the lithium ion battery module 28, for example,when temperature reaches an upper threshold.

As described above, the control module 32 may generally controloperation of the vehicle 10. In other words, the control module 32 mayenable de-rating/re-rating of the battery system 12 by controlling theoperation of the electrical energy generator 42 (e.g., output voltage orcurrent) and/or state of the relay 46. In some embodiments, thefunctions performed by the control module 32 may be split between abattery control module and a vehicle control module. To help illustrate,a block diagram of the lithium ion battery module 28 is described inFIG. 6.

As depicted, the lithium ion battery module 28 is electrically coupledto the bus 26 via battery terminals 54. Additionally, the batteryterminals 54 are selectively connected to the battery cells 56 via therelay 46. More specifically, operation of the relay 46 may be controlledby a battery control module 58. For example, the battery control module58 may instruct the relay 46 to change to a specific state (e.g., thefirst state or the second state), which may be used to de-rate/re-ratethe battery system 12.

As described above, the battery system 12 may be de-rated to regulatetemperature of the lithium ion battery module 28, for example, bylimiting the amount of charging/discharging performed. Accordingly, thebattery control module 58 may be communicatively coupled to one or moresensors 60, which measure operational parameters of the lithium ionbattery module 28. For example, the sensors 60 may include a temperaturesensor 60, which measures the temperature of the lithium ion batterymodule 28, and a state of charge sensor, which measures the state ofcharge of the lithium ion battery module 28. Additionally oralternatively, the sensors 60 may measure other operational parametersthat may be used by the battery control module 58 to determine the stateof charge of the lithium ion battery module 28, such as a voltage and/orcurrent sensor. For example, using a voltage sensor, the battery controlmodule 58 may determine the state of charge of the lithium ion based onthe open-circuit voltage versus state of charge relationship describedby the NMC/LTO voltage curve 48.

Additionally, as depicted, the battery control module 58 iscommunicatively coupled to the vehicle control module 62 via a signalconnector 64. More specifically, the battery control module 58 and thevehicle control module 62 may coordinate control to de-rate/re-rate thebattery system 12. Accordingly, in some embodiments, the vehicle controlmodule 62 may control operation of the electrical energy generator 42.For example, the vehicle control module 62 may instruct the electricalenergy generator 42 to output a particular voltage (e.g., charge voltageand/or current (e.g., charge current). Additionally, the vehicle controlmodule 62 may inform the battery control module 58 when electricalenergy is being generated, for example, during regenerative braking.

Furthermore, during repeated charging/discharging of the lithium ionbattery module 28, the chemical reactions within the battery module 28may release gases and produce heat. Accordingly, as depicted, thelithium ion battery module 28 includes a vent system 66, which releasethe produced gases once the pressure within the battery module 28reaches a threshold amount. In some embodiments, the vent system 66 mayrelease the produced gas along with the produced heat. Additionally, thelithium ion battery module 28 may include a thermal system 68 to helpcool the battery module 28 by exchanging heat with the surroundenvironment.

More specifically, the thermal system 68 may include a passive coolingsystem, which utilizes passive cooling components, such as a coolingfin. To help illustrate, a lithium ion battery module 28 that utilizes apassive thermal system 68 is shown in FIGS. 7A and 7B. In other words,FIGS. 7A and 7B incorporates features of present embodiments. Asdepicted in FIG. 7A, the lithium ion battery module 28 includes ahousing 70, battery terminals 54, a gas vent 72 (e.g., part of the ventsystem 66), and cooling fins 74 (e.g., part of the passive thermalsystem 68). More specifically, the gas vent 72 may be connected to ahose (not depicted), which guides the vent gas to an exhaust.Additionally, the hose connected to the vent 72 may include an overpressure valve (not depicted) to control the flow of vent gas throughthe exhaust hose. More specifically, the over pressure valve may open tovent gas when a threshold amount of pressure is present.

Additionally, as depicted, the cooling fins 74 are disposed on the sideof the battery housing 70. More specifically, the cooling fins 74 mayextract heat generated from the battery cells 56 and release heat intothe surrounding environment. To help illustrate, an exploded view of thelithium ion battery module 28 is described in FIG. 7B. As depicted,thermal pads 76 may be disposed between the battery cells 56 and thecooling fins 74. In some embodiments, the thermal pads 76 may improveheat extraction from the battery cells 56 by reducing the air gapbetween the cooling fins 74 and the battery cells 56.

Furthermore, in the depicted embodiment, the cooling fins 74 areseparated into two portions. More specifically, the cooling fins 74 maybe aligned with the two rows of battery cells 56. In some embodiments,aligning a cooling fin 74 to each row of battery cells 56 may improveheat extraction because a partition that separates the rows generallydoes not produce heat. As such, extending the cooling fins 74 over thepartition may increase production costs and cause a heat gradient tooccur, which may reduce heat transfer efficiency.

To facilitate heat exchange with the surrounding environment, thecooling fins 74 may be positioned so that air flows over the coolingfins 74. For example, the cooling fins 74 may be placed next to airducts in the vehicle, which enables outside air to flow into the vehicle10. In some embodiments, the ducts may be positioned so that motion ofthe vehicle 10 cause air to flow into the vehicle 10, remove heat fromthe cooling fins 74, and exit the vehicle 10.

As such, the vent system 66, which may include the gas vent 72, and thethermal system 68, which include the thermal pad 76, cooling fins 74,may be used to help regulate the temperature of the lithium ion batterymodule 28. However, in extreme conditions, such as high environmentaltemperature or a long period of operation, they may still beinsufficient to maintain the lithium ion battery module 28 at desiredtemperatures. As such, the present disclosure utilizesde-rating/re-rating strategies to supplement the cooling provided by thevent system 66 and the thermal system 68. In fact, in some embodiments,the de-rating/re-rating techniques may even enable the lithium ionbattery module 28 to utilize only a passively cooled thermal system 68,which may reduce manufacturing complexity and/or costs.

Reactive Control Scheme

As described above, the de-rating/re-rating techniques may beimplemented in a reactive control scheme and/or an intelligent (e.g.,predictive) control scheme. To help illustrate, an embodiment of acontrol module 32A implementing a reactive control scheme is describedin FIG. 8. As depicted, the control module 32A may receive a measuredtemperature of the lithium ion battery 28. In some embodiments, thetemperature of the lithium ion battery 28 may be determined via atemperature sensor 60 coupled to the lithium ion battery 28.

Based on the measured temperature, the control module 32A may determinebattery parameter setpoints 80 to implement in the battery system 12. Insome embodiments, the battery parameter setpoints 80 may includecharging current produced by the electrical energy generator 42,charging voltage produced by the electrical energy generator 42,discharging current output by the lithium ion battery module 28,discharging voltage output by the lithium ion battery module 28, or anycombination thereof. Thus, the control module 32A may determine thebattery parameter setpoints 80 to implement de-rating and/or re-ratingthe battery system 12. For example, the control module 32A may instructthe electrical energy generator 42 to reduce charging current to reduceamount of charging and discharging performed by the lithium ion batterymodule 28, thereby reducing battery temperature.

More specifically, in a reactive control scheme, the control module 32Amay determine the battery parameter setpoints 80 using one or moretemperature thresholds 82. For example, in some embodiments, the controlmodule 32A may compare the measured battery temperature 78 with atemperature threshold 82. When the measured battery temperature 78 isgreater than the temperature threshold 82, the control module 32A maydetermine battery parameter setpoints 80 to de-rate the battery system12. Additionally, when the measured battery temperature reduces below atemperature threshold 82, the control module 32A may determine batteryparameter setpoints 80 to re-rate the battery system 12.

To help illustrate, an embodiment of a process 84 for reactivelyde-rating the battery system 12 in a passive parallel architecture isdescribed with respect to FIG. 9. Generally, the process 84 includesgenerating electrical energy (process block 86), determining the lithiumion battery temperature (process block 88), and determining whether thelithium ion battery temperature is greater than a temperature threshold(decision block 90). When the lithium ion battery temperature is notgreater than the threshold, the process 84 includes maximizing captureof electrical energy with the lithium ion battery (process block 92) andsupplying electrical power primarily from the lithium ion battery(process block 94). On the other hand, when the lithium ion batterytemperature is greater than the temperature threshold, the process 84includes de-rating the lithium ion battery system (process block 96) andreducing charge power to and discharge power from the lithium ionbattery (process block 98). In some embodiments, process 84 may beimplemented with instructions stored on one or more tangible,non-transitory, computer-readable medium, such as memory 36, andexecuted by one or more processors, such as processor 34.

Accordingly, in some embodiments, the control module 32A (e.g., thevehicle control module 62) may instruct the electrical energy generator42 to generate electrical energy (process block 86). As described above,the electrical energy generator 42 (e.g., electric motor 22) maygenerate electrical energy during regenerative braking by converting themechanical energy produced by the movement of the vehicle 10 intoelectrical energy. Additionally or alternatively, the electrical energygenerator 42 (e.g., alternator 18) may convert mechanical energyproduced by the internal combustion engine 24 into electrical energy.

Additionally, the control module 32A (e.g., battery control module 58)may determine the lithium ion battery temperature 78 (process block 88).More specifically, the battery control module 58 may poll a temperaturesensor 60 coupled to the battery cells 56 to determine temperaturelithium ion battery module 28. In some embodiments, the battery controlmodule 58 may determine the temperature of the lithium ion batterymodule 28 in response to determining that electrical energy is beinggenerated, for example, from the vehicle control module 62. In otherembodiments, the battery control module 58 may periodically determinetemperature of the lithium ion battery module 28 during operation, forexample, every five seconds.

The control module 32A may then determine whether the lithium ionbattery temperature 78 is greater than a temperature threshold 82(decision block 90). Generally, the temperature threshold 82 may be setto reduce the likelihood of degrading performance and/or life span ofthe lithium ion battery module 28 due to temperature. As such, thetemperature threshold 82 may be predetermined and stored in memory 36.Thus, the control module 32A may retrieve the temperature threshold 82from memory 36 and compare it with the lithium ion battery temperature78.

Additionally, since the operation of the lithium ion battery module 28may be reduced due to de-rating, the temperature threshold may be set tobalance any performance and/or lifespan degradation of the lithium ionbattery module 28 due to temperature and the effect reduced operation ofthe lithium ion battery module 28 may have on vehicle operation. Forexample, the temperature threshold may be set at 70° C. to increase theduration the lithium ion battery module 28 is fully operational, therebyreducing effects of de-rating on operation of the vehicle 10 whileincreasing the likelihood of performance and/or life span degradation ofthe lithium ion battery module 28. On the other hand, the temperaturethreshold may be set at 55° to reduce the duration the lithium ionbattery is fully operational, thereby increasing effects of de-rating onoperation of the vehicle 10 while decreasing the likelihood ofperformance and/or life span degradation of the lithium ion batterymodule 28.

When the control module 32A determines that the lithium ion batterytemperature 78 is not greater than the temperature threshold, thecontrol module 32A may enable maximizing capture of the generatedelectrical energy using the lithium ion battery module 28 (process block92). In other words, the lithium ion battery module 28 may utilize amaximum storage capacity (e.g., up to 100% SOC) to capture the generatedelectrical energy.

For example, when the lithium ion battery module 28 is a NMC/LTO batteryand the electrical energy generator 42 (e.g., alternator 18 or theelectric motor 22) outputs a variable voltage, the control module 32Amay instruct the electrical energy generator 42 to output a voltagegreater than 16.2 volts, thereby enabling the lithium ion battery module28 to capture electrical energy up to 100% state of charge.Additionally, since the maximum open-circuit voltage of the lead-acidbattery module 30 is 12.9 volts, the voltage output by the electricalenergy generator 42 may also enable the lead-acid battery module 30 tocapture electrical energy up to 100% state of charge. In other words,the full storage capacity of the battery system 12 may be utilized whenthe lithium ion battery temperature 78 is not greater than thetemperature threshold.

Furthermore, since a maximum storage capacity of the lithium ion batterymodule 28 may be utilized, the open-circuit voltage of the lithium ionbattery module 28 may end up being higher than the open-circuit voltageof the lead-acid battery module 30. For example, when a NMC/LTO batteryis charged above 25% state of charge, the open-circuit voltage should behigher than the open-circuit voltage of the lead-acid battery module 30.

Accordingly, when the open-circuit voltage of the lithium ion batterymodule 28 is higher than the open-circuit voltage of the lead-acidbattery module 30, the electrical power may be supplied to the vehicle'selectrical system primarily from the lithium ion battery module 28(process block 94). As described above, the open-circuit voltage of thelithium ion battery module 28 may decrease at it discharges. Thus, thelead-acid battery module 30 may also begin supplying electrical powerwhen the open-circuit voltage of the lithium ion battery module 28 nearsthe open-circuit voltage of the lead-acid battery module 30.

As such, when the lithium ion battery temperature 78 is below thetemperature threshold 82, the lithium ion battery module 28 may utilizea maximum storage capacity to capture electrical energy and provideelectrical power by itself until it nears the open-circuit voltage ofthe lead-acid battery module 30. In other words, the lithium ion batterymodule 28 may repeatedly charge and discharge to supply electrical powerto the electrical system 44. Additionally, the amount of energy storedin the lithium ion battery module 28 may be as high as 100% state ofcharge. However, as described above, repeatedly charging/discharging thelithium ion battery module 28 may increase the temperature of thelithium ion battery module 28. In other words, the longer the lithiumion battery module 28 is fully utilized, the lithium ion batterytemperature 78 may gradually increase.

On the other hand, when the control module 32A determines that thelithium ion battery temperature 78 is greater than the temperaturethreshold 82, the control module 32A may de-rate the lithium ion batterysystem (process block 96). More specifically, the control module 32A mayde-rate the lithium ion battery system by limiting the electrical energycaptured by the lithium ion battery module 28, for example, bycontrolling charging current produced by the electrical energy generator42, charging voltage produced by the electrical energy generator 42,discharging current output by the lithium ion battery module 28,discharging voltage output by the lithium ion battery module 28, or anycombination thereof.

For example, when the lithium ion battery module 28 is a NMC/LTO batteryand the electrical energy generator 42 outputs a variable voltage, thecontrol module 32A (e.g., the vehicle control module 62) may instructthe electrical energy generator 42 to output a reduced voltage and/or areduced current. In some embodiments, the control module 32A mayinstruct the electrical energy generator 42 to output 12.9 volts so thatthe lead-acid battery module 30 may be charged up to 100% state ofcharge while the lithium ion battery module 28 may only be charged up to25% state of charge. By further example, the control module 32A mayinstruct the regenerative braking system to output 12.7 volts so thatthe lead-acid battery module 30 may be charged up to 85% state of chargewhile the lithium ion battery module 28 may only be charged up to 15%state of charge.

On the other hand, when the electrical energy generator 42 has a fixedoutput voltage (e.g., 13.3 volts), the control module 32A (e.g., thevehicle control module 62) may instruct the electrical energy generator42 to reduce current output, duration electrical energy is generated, orboth. For example, the control module 32A may instruct the alternator 18and/or the electric motor 22 to reduce the output current to 150 amps sothat the lithium ion battery module 28 may only be charged to 15% stateof charge and the lead-acid battery module 30 may only be charged to 85%state of charge. Additionally or alternatively, control module 32A mayinstruct the alternator 18 and/or the electric motor 22 to ceasegenerating electrical energy once the batteries 28 and 30 reach theirtarget states of charge.

Thus, the amount of energy captured (e.g., charging) and stored in thelithium ion battery module 28 may be reduced. Additionally, since theopen-circuit voltage of the lithium ion battery module 28 and thelead-acid battery module 30 may be close or the same and lead-acidbattery module 30 has a higher energy density, the charge power to andthe discharge power from the lithium ion battery 28 may be reduced(process block 98). In this manner, de-rating the battery system 12 mayreduce the amount of charging/discharge performed by the lithium ionbattery module 28, which may facilitate cooling the lithium ion batterymodule 28.

In some embodiments, the rate of cooling the lithium ion battery module28 may be related to the reduction in charging/discharging and/or theamount of stored energy. For example, the lithium ion battery module 28may cool at a faster rate when the voltage output by the electricalenergy generator 42 is reduced to 12.7 volts, which limits the lithiumion battery module 28 to 15% SOC, as compared to 12.9 volts, whichlimits the lithium ion battery module 28 to 25% SOC. More specifically,when the output voltage is 12.7 volts, the lithium ion battery module 28may capture/store less electrical energy, which reducescharging/discharging performed and enables the lithium ion batterymodule 28 to cool at a faster rate.

As such, in some embodiments, the control module 32A may instruct theelectrical energy generator 42 to operate (e.g., output a specificvoltage or current level) based on a temperature of the lithium ionbattery module 28 and/or a desired rate of cooling. For example, thecontrol module 32A may instruct the electrical energy generator 42 tooutput 12.9 volts when the temperature threshold is exceeded andinstruct the alternator 18 and/or the electric motor 22 to output 12.7when a higher temperature threshold is exceeded.

Additionally, as described in process 84, the control module 32A maycompare the lithium ion battery temperature to the temperature thresholdwhenever electrical energy is generated. As such, when the controlmodule 32A determines that the temperature of the lithium ion batterymodule 28 has decreased below the temperature threshold, the controlmodule 32A may re-rate the battery system 12 to enable the lithium ionbattery module 28 to resume utilizing its full storage capacity. Inother embodiments, lithium ion battery module 28 may resume utilizingits full storage capacity at a lower temperature threshold, such as 40°C.

Furthermore, although process 84 is described in relation to statictemperature thresholds, in other embodiments, the control module 32A maymonitor (e.g., determine) the rate of change of the lithium ion batterytemperature 78. For example, in decision block 90, the control module32A may compare the rate at which the lithium ion battery temperature 78is changing to a temperature threshold, which describes a threshold rateof temperature change. Thus, when the rate of change is greater, thecontrol module 32A may de-rate the battery system 12.

To further illustrate, an embodiment of a process 100 for reactivelyde-rating the battery system 12 in a semi-passive parallel architectureis described in FIG. 10. Generally, the process 100 includes generatingelectrical energy (process block 102), determining the lithium ionbattery temperature (process block 104), and determining whether thebattery temperature is greater than a lower (e.g., first) temperaturethreshold (decision block 106). When the battery temperature is notgreater than the lower temperature threshold, the process 100 includesmaximizing capture of the electrical energy with the lithium ion battery(process block 108) and supplying power primarily from the lithium ionbattery (process block 110). On the other hand, when the batterytemperature is greater than the lower temperature threshold, the process100 may include determining whether the battery temperature is greaterthan a higher (e.g., second) temperature threshold (decision block 112).When the temperature is not greater than the higher temperaturethreshold, the process 100 includes reducing charge power to anddischarge power from the lithium ion battery (process block 114). On theother hand, when the battery temperature is greater than the highertemperature threshold, the process 100 may include disconnecting thelithium ion battery system (process block 118), capturing the electricalenergy with the lead-acid battery (process block 120), and supplyingpower only from the lead-acid battery (process block 122). In someembodiments, process 100 may be implemented by instructions stored onone or more tangible, non-transitory, computer readable medium, such asmemory 36, and executed by one or more processors, such as processor 34.

Accordingly, similar to process block 86, the control module 32A (e.g.,the vehicle control module 62) may instruct the electrical energygenerator 42 to generate electrical energy (process block 102).Additionally, similar to process block 88, the control module 32A (e.g.,battery control module 58) may determine the lithium ion batterytemperature 78 (process block 104).

The control module 32A may then determine whether the lithium ionbattery temperature 78 is greater than a lower temperature threshold(decision block 106). In some embodiments, the lower temperaturethreshold may be predetermined and stored in memory 36. Thus, thecontrol module 32A may retrieve the lower temperature threshold frommemory 36 and compare it with the lithium ion battery temperature 78.For example, the lower temperature threshold may be 55° C.

When the control module 32A determines that the lithium ion batterytemperature 78 is not greater than the lower temperature threshold, thecontrol module 32A (e.g., battery control module 58) may instruct therelay 46 to be in the first state, which connects the lithium ionbattery module 28 in parallel with the lead-acid battery module 30.Accordingly, similar to process block 92, the control module 32A maymaximize capture of the generated electrical energy using the lithiumion battery module 28 (process block 108) and, similar to process block94, supply electrical power to the vehicle's electrical system 44 may beprimarily from the lithium ion battery module 28 (process block 110).

When the control module 32A determines that the lithium ion batterytemperature 78 is greater than the lower temperature threshold, thecontrol module 32A may determine whether the battery temperature 78 isgreater than a higher temperature threshold (decision block 112).Similar to the lower temperature threshold, in some embodiments, thehigher temperature threshold may be predetermined and stored in memory36. Thus, the control module 32A may retrieve the higher temperaturethreshold from memory 36 and compare it with the lithium ion batterytemperature 78. For example, the higher temperature threshold may be 70°C.

When the control module 32A determines that the lithium ion batterytemperature 78 is not greater than the higher temperature threshold, thecontrol module 32A (e.g., battery control module 58) may instruct therelay 46 to remain in the first state and de-rate the lithium ionbattery system to reduce charge power to and discharge power from thelithium ion battery 28 (process block 114). More specifically, similarto process block 96, the control module 32A may control the chargingcurrent produced by the electrical energy generator 42, charging voltageproduced by the electrical energy generator 42, discharging currentoutput by the lithium ion battery module 28, discharging voltage outputby the lithium ion battery module 28, or any combination thereof.

When the control module 32A determines that the battery temperature isgreater than the higher temperature threshold, the control module 32A(e.g., battery control module 58) may instruct the relay 46 to change tothe second state and disconnect the lithium ion battery module 28(process block 118). Since the lithium ion battery module 28 isdisconnected, the lead-acid battery module 30 may capture the generatedelectrical energy (process block 120) and supply electrical power byitself (process block 122). When the lithium ion battery module 28 isdisconnected, it may cease charging/discharging and maintain its stateof charge. As such, disconnecting the lithium ion battery module 28 mayprovide the fastest rate of cooling. However, providing electrical powerwith only the lead-acid battery module 30 may affect vehicle performancebecause the lead-acid battery module 30 may power more electricaldevices. As such, in some embodiments, the lithium ion battery module 28may be disconnected as a last resort.

Similar to process 84, the control module 32A in process 100 may comparethe lithium ion battery temperature 78 to the lower temperaturethreshold and the upper temperature threshold whenever electrical energyis generated. As such, when the control module 32A determines that thelithium ion battery temperature 78 has decreased below the uppertemperature threshold, the control module 32A may instruct the relay 46to reconnect the lithium ion battery module 28, but limit the electricalenergy capture by the lithium ion battery module 28. Additionally, whenthe control module 32A determines that the temperature of the lithiumion battery module 28 has decreased below the lower temperaturethreshold, the control module 32A may re-rate the battery system 12 andenable the lithium ion battery module 28 to resume utilizing its fullstorage capacity. In other embodiments, lithium ion battery module 28may resume utilizing its full storage capacity at an even lowertemperature threshold, such as 40° C.

Furthermore, although process 100 is described in relation to statictemperature thresholds, in other embodiments, the control module 32A maymonitor the rate of change of the lithium ion battery temperature 78.For example, in decision block 106, the control module 32A may comparethe rate of change of the lithium ion battery temperature 78 to a lowertemperature threshold, which describes a lower threshold rate oftemperature change. Additionally, in decision block 112, the controlmodule 32A may compare the rate of change of the lithium ion batterytemperature 78 to a higher temperature threshold, which describes ahigher threshold rate of temperature change. Thus, when the rate ofchange is greater than the lower temperature threshold, the controlmodule 32A may de-rate the battery system and, when the rate of changeis greater than the higher temperature threshold, the control module 32Amay disconnect the lithium ion battery module 28.

As such, the reactive control scheme described above may facilitatecontrolling temperature of the lithium ion battery module 28 based atleast in part on a currently determined lithium ion battery temperature78 and one or more temperature thresholds 82. More specifically, thede-rating/re-rating techniques described may facilitate cooling alithium ion battery module 28 in the battery system 12 by reactivelycooling the lithium ion battery module 28 when the current determinedtemperature reaches a temperature threshold 82.

To help illustrate, results from testing a vehicle using only a passivethermal system and a reactive de-rating scheme under five differentoperating scenarios are described below. The operating parameters foreach of the scenarios are summarized below in Table 1.

TABLE 1 Operating Parameters of Vehicle Testing Scenarios 1 2 3 4 5Environment Boston Boston Miami Miami 45° C. Driving Pattern 2 × 1 hr 2× 1 hr 2 × 1 hr 2 × 1 hr 3.5 hrs NEDC BOL/EOL BOL EOL BOL EOL BOL

As described in Table 1, in the fifth scenario, the vehicle was equippedwith a lithium ion battery at the beginning of life (BOL) and driven forthree and a half hours in a 45° C. environment. More specifically, inthe fifth scenario the vehicle was driven in eleven back-to-back NewEuropean Drive Cycle (NEDC) cycles. Additionally, in the first andsecond scenarios, the vehicle was driven in Boston, Mass. for one hourtwice a day. Furthermore, in the third and fourth scenarios, the vehiclewas driven in Miami, Fla. for one hour twice a day. More specifically,in the first through fourth scenarios, the vehicle was driven for onehour from the eighth hour to the ninth hour of the day and again for onehour from the seventeenth hour to the eighteenth hour of the day.

Additionally, to determine effect age of the lithium ion battery mayhave on the vehicle operation, the vehicle was tested when equipped witha lithium ion battery at different stages of life. As described in Table1, the vehicle was equipped with a lithium ion battery at the beginningof life (BOL) in the first and third scenarios. On the other hand, thevehicle was equipped with a lithium ion battery at the end of life (EOL)in the second and fourth scenarios.

Generally, as a lithium battery ages the internal resistance maygradually increase. To help illustrate, the internal resistance of alithium ion battery operated in Boston over its life is shown in FIG.11. More specifically, FIG. 11 is a plot that describes the internalresistance of the lithium ion battery with a resistance curve 124 overits eight year life, in which the years are shown on the X-axis and theinternal resistance is shown on the Y-axis.

As described by the resistance curve 124, the internal resistance of thelithium ion battery at year eight (e.g., EOL) was approximately 1.12times its internal resistance at year zero (e.g., BOL). Generally, it isdesirable for the internal resistance of the lithium ion battery to bemaintained below 1.39 times its beginning of life internal resistance.In some embodiments, when the internal resistance increases more than1.39 times, the operational efficiency of the lithium ion battery may bedegraded. For example, the increased internal resistance may cause thelithium ion battery to heat up more quickly.

Additionally, even though the internal resistance increased 1.12 timesfrom its beginning of life internal resistance, the temperature of thelithium ion battery did not appear to be drastically affected. To helpillustrate, the temperature of the lithium ion battery and the ambienttemperature of the vehicle in the first scenario and the second scenarioare described in FIGS. 12 and 13 respectively. More specifically, FIG.12 is a plot that describes the temperature of the lithium ion batteryat the beginning of life with a battery temperature curve 126 andambient temperature of the vehicle with a vehicle temperature curve 128in the first scenario (e.g., over 24 hours), in which the hours of theday are shown on the X-axis and the temperature is shown on the Y-axis.Similarly, FIG. 13 is a plot that describes the temperature of thelithium ion battery at the end of life with a battery temperature curve130 and ambient temperature of the vehicle with a vehicle temperaturecurve 132 in the second scenario (e.g., over 24 hours), in which thehour of the day is shown on the X-axis and the temperature is shown onthe Y-axis.

As described by the battery temperature curves 126 and 130, thetemperature of the lithium ion battery was approximately the sameregardless of whether it was at the beginning of life or the end oflife. More specifically, in both the first and second scenarios, thebattery temperature remained generally constant from hour zero to houreight when the vehicle was not in operation. Between hour eight and hournine, the battery temperature increased as the vehicle was driven for anhour. The battery temperature then gradually decreased from hour nine tohour seventeen when the vehicle was not in operation. Between hourseventeen and hour eighteen, the battery temperatures rose again whenthe vehicle was driven for an hour. Finally, the battery temperaturesagain gradually decreased from hour eighteen to hour twenty-four whenthe vehicle was not in operation.

Additionally, as described by the battery temperature curves 126 and130, the temperatures of the lithium ion batteries were maintained wellbelow 70° C. In other words, the of the lithium ion battery temperatureswere maintained below a temperature threshold of 70° C. As such, inBoston, the passive cooling system was sufficient to maintain thetemperature of the lithium ion battery within a desired range, even whenthe lithium ion battery is at its end of life.

However, as described above, the environmental temperature may affectthe temperature of the lithium ion battery. Accordingly, the vehicle wasalso tested in a harsher environment. More specifically, the vehicle wasdriven in Miami, which has a higher environmental temperature thanBoston.

As expected, the higher temperatures in Miami caused the internalresistance of the lithium ion battery to increase at a faster rate. Tohelp illustrate, the internal resistance of the lithium ion batteryoperated in Miami, Fla. over its life is described in FIG. 14. Morespecifically, FIG. 14 is a plot that describes the internal resistanceof the lithium ion battery with a resistance curve 134 over its eightyear life, in which the years are shown on the X-axis and the internalresistance is shown on the Y-axis.

As described by the resistance curve 134, the internal resistance of thelithium ion battery at year eight (e.g., EOL) was approximately 1.24times its internal resistance at year zero (e.g., BOL). Thus, even withthe higher environmental temperatures, the internal resistance increasedby less than the 1.39 times threshold. Additionally, even though theinternal resistance of the lithium ion battery increased by a largeramount, the temperature of the lithium ion battery still did not appearto be drastically affected.

To help illustrate, the temperature of the lithium ion battery and theambient temperature of the vehicle in the third scenario and the fourthscenarios are described in FIGS. 15 and 16 respectively. Morespecifically, FIG. 15 is a plot that describes the temperature of thelithium ion battery at the beginning of life with a battery temperaturecurve 136 and ambient temperature of the vehicle with a vehicletemperature curve 138 in the third scenario (e.g., over 24 hours), inwhich the hours of the day are shown on the X-axis and the temperatureis shown on the Y-axis. Similarly, FIG. 16 is a plot that describes thetemperature of the lithium ion battery at the end of life with a batterytemperature curve 140 and ambient temperature of the vehicle with avehicle temperature curve 142 in the fourth scenario (e.g., over 24hours), in which the hour of the day is shown on the X-axis and thetemperature is shown on the Y-axis.

As in Boston, the temperature of the lithium ion battery was generallythe same regardless of whether it was at the beginning of life or theend of life. Additionally, as described by the battery temperaturecurves 136 and 140, the temperatures of the lithium ion batteries weremaintained below 70° C. In other words, even with the elevatedenvironmental temperatures, the lithium ion batteries were maintainedbelow a temperature threshold of 70° C. As such, even in Miami, thepassive cooling system was sufficient to maintain the temperature of thelithium ion battery within a desired range.

A summary of the first four scenarios is presented below in table 2.

TABLE 2 Summary of Testing Results BOL/EOL R % increase % De-rated MiamiBOL N/A 0% EOL 124% 0% Boston BOL N/A 0% EOL 112% 0%

As described in Table 2, the internal resistance of the lithium ionbattery operated in Miami increased 124% from the beginning of life tothe end of life. Additionally, the internal resistance of the lithiumion battery operated in Boston increased 112% from the beginning of lifeto the end of life. As such, in both Boston and Miami, the internalresistance of the lithium ion battery increased by less than an upperthreshold amount of 139%.

Moreover, as described in Table 2, the lithium ion battery was notde-rated in any of the first four scenarios. In other words, even inharsh conditions, such as Miami, a passive cooling system may besufficient to maintain the temperature of the lithium ion battery module28 in a desirable range (e.g., less than a temperature threshold of 70°C.). In other words, since most driving environments are less taxingthan Miami, the passive cooling system may be sufficient when drivetimes are less than one hour.

However, since lithium ion battery temperature gradually increases overoperation, the passive cooling system may eventually become insufficientwith increased drive times and de-rating/re-rating techniques may beutilized to facilitate controlling temperature. The fifth scenario isused to help illustrate. As described above, in the fifth scenario, thevehicle was driven for eleven back-to-back NEDC drive cycles (e.g.,three hours and forty minutes) in a temperature controlled environment.

The temperature of the lithium ion battery gradually increased asdriving duration increased. To help illustrate, the results of the fifthscenario are described in FIGS. 17A-17C. More specifically, FIG. 17A isa plot that describes the temperature of the lithium ion battery with abattery temperature curve 148 in the fifth scenario, in which the hoursare shown on the X-axis and the temperature is shown on the Y-axis.

In the fifth scenario, a de-rating (e.g., lower) temperature threshold144 was set at 60° C. and a start-stop (e.g., higher) temperaturethreshold 146 was set at 68° C. More specifically, the lithium ionbattery began to be de-rated once the temperature of the lithium ionbattery reached the de-rating temperature threshold 144. Accordingly, asdescribed by the battery temperature curve 148, the temperature of thelithium ion battery increased from 45° C. at hour zero to 60° C. atapproximately hour 2.25. Once the de-rating temperature threshold 144was reached, the battery system was reactively de-rated. Accordingly,the temperature of the lithium ion battery subsequently increased at aslower rate from hour 2.25 to hour 3.5.

Additionally, if the lithium ion battery temperature had reached thestart-stop temperature threshold 146, the lithium-ion battery would havebeen disconnected. In fact, as long the lithium-ion battery remainedconnected, it was possible to perform start-stop operations. In otherwords, even though the lithium ion battery was de-rated between hour2.25 and hour 3.5, the vehicle was still able to disable the internalcombustion engine when the vehicle was idle and to re-crank the internalcombustion engine when propulsion was desired.

To help illustrate, the effects of de-rating the lithium ion battery aredescribed in FIGS. 17B and 17C. More specifically, FIG. 17B is a plotthat describes energy capture efficiency with a regenerative efficiencycurve 150 and the amount of regenerative energy captured with aregenerative throughput curve 152 in the fifth scenario, in which the inwhich the hours are shown on the X-axis, the regenerative efficiency isshown on a first Y-axis, and regenerative energy throughput is shown ona second Y-axis.

As described by the regenerative efficiency curve 150, the energycapture efficiency of the battery system was generally maintained at100% from hour zero to approximately hour 2.25 because the energycapture capabilities of the lithium-ion battery were maximized. However,once de-rated, the energy capture efficiency of the battery systemdecreased. More specifically, the energy capture efficiency may havedecreased because de-rating caused the lead-acid battery to be used tocapture a greater portion of the generated electrical energy.

Nevertheless, even after the battery system was de-rated, the electricalenergy generated during regenerative braking continued to be captured.Accordingly, as depicted, the regenerative throughput curve 152continues to increase during the entire period of operation. However,since de-rating the battery system decreased the energy captureefficiency, the rate at which the electrical energy is captureddecreased. Accordingly, as depicted, the slope of the regenerativethroughput curve 152 decreases at approximately hour 2.25.

Even though the battery system was de-rated, start-stop operations werestill possible. To help illustrate, FIG. 17C is a plot that describesthe expected (e.g., un-de-rated) current of the lithium ion battery witha drive cycle current curve 154 and the actual current of the lithiumion battery with a de-rated current curve 156, in which the in which thehours are shown on the X-axis and the current is shown on the Y-axis. Inthe depicted embodiment, positive current is intended to describecharging current supplied to the lithium ion battery and negativecurrent is intended to describe discharging current supplied by thelithium ion battery.

As described by the drive cycle current curve 154 and the de-ratedcurrent curve 156, the actual current of the lithium ion battery wasgenerally as expected between hour zero to approximately hour 2.25. Morespecifically, during that period, the lithium ion battery was chargedwith a relatively constant 200 amps during regenerative braking.Additionally, the lithium ion battery output a relatively constant 80amps to the electrical system of the vehicle. Furthermore, the lithiumion battery periodically output pulses of approximately 180 amps tocrank the internal combustion engine (e.g., during a start-stopoperation).

However, once the battery system was de-rated, the actual current of thelithium ion battery began to vary from the expected current. Morespecifically, the lithium ion battery was charged with a decreasingcurrent, thereby reducing the electrical energy captured by the lithiumion battery. Nevertheless, during this period, the lithium ion batterywas still able to output a relatively constant 80 amps to the electricalsystem of the vehicle and output pulses of 180 amps to crank theinternal combustion engine (e.g., during a start-stop operation). Assuch, even when the battery system was de-rated to control temperatureof the lithium ion battery, efficiency benefits provided by mHEVs maystill be utilized.

As illustrated by the above example, operation of the battery system 12may be controlled in a reactive control scheme based on currentoperation of the lithium ion battery. For example, a reactive controlscheme may de-rate/re-rate the battery system based on a presentlymeasured operational parameter (e.g., measured temperature 78) and oneor more thresholds governing the operational parameters (e.g.,temperature thresholds 82). In this manner, a reactive control schememay improve performance and/or life span of lithium ion battery byreactively maintaining lithium ion battery temperature within a desiredtemperature range.

Intelligent Control Scheme

To further improve performance and/or life span of the lithium ionbattery, operation of the battery system 12 may be controlled in anintelligent (e.g., predictive) control scheme based on current as wellas predicted future operation of the lithium ion battery module 28. Forexample, an intelligent control scheme may de-rate/re-rate the batterysystem based on a presently measured operational parameter as well as apredicted trajectory of the operational parameter, one or more modelsthat facilitate determining the projected trajectory, and an objectivefunction that facilitates determining battery parameters setpoints. Inthis manner, an intelligent control scheme may further improveperformance and/or life span of the lithium ion battery module 28 byguiding lithium ion battery temperature along a target temperaturetrajectory and/or maintaining the lithium ion battery temperature belowa temperature threshold.

More specifically, as described above, lithium ion battery temperaturemay affect performance and/or life span of the lithium ion battery. Forexample, exposing the lithium ion battery to higher temperatures maycause internal resistance to increase at a faster rate, therebyincreasing the aging rate of the lithium ion battery module 28.Additionally, de-rating the battery system may affect the operation ofthe vehicle 10, for example, by reducing electrical energy capture andthus fuel economy of the vehicle 10.

Accordingly, in some embodiments, using an intelligent control schememay enable the battery system to improve battery system 12 operation bybalancing effects various aspects of the battery system 12, such astemperature of the lithium ion battery module 28, life span of thelithium ion battery module 28, fuel economy contribution by the lithiumion battery module 28, and the like. Moreover, the intelligent controlscheme may enable accounting for the predicted effects on the variousfactors in future operation. For example, taking into account futureoperation, the battery system 12 may be de-rate earlier and moregradually, thereby reducing effects on operation of the vehicle 10caused by de-rating.

To help illustrate, an embodiment of a control module 32B used toimplement an intelligent control scheme is described in FIG. 18. Asdepicted, the control module 32B receives input operational parametersdetermined for the present time step, which include battery current 158,bus voltage 160, battery temperature 162, and optionally environmentaltemperature 163. In some embodiments, the input operational parametersmay be measured by one or more sensors 60. For example, a current sensorelectrically coupled to terminals 54 of the lithium ion battery module28 may facilitate determining the battery current 158 by measuring thecurrent supplied to the lithium ion battery (e.g., charging current) andthe current supplied from the lithium ion battery (e.g., dischargingcurrent). Additionally, a voltage sensor electrically coupled to the bus26 may facilitate determining the bus voltage 160 by measuring voltageon the bus 26. Furthermore, temperature sensors 60 may facilitatedetermining the battery temperature 162 by measuring temperature of thelithium ion battery module 28 and/or determining the environmentaltemperature 163 by measuring temperature of environment surrounding thevehicle 10. Additionally or alternatively, the environmental temperature163 may be indirectly determined based on other operational parameters.

As depicted, the control module 32B also includes one or more models andan objective function 165. In the depicted embodiment, the controlmodule 32 includes a thermal predictive model 164, a driving patternrecognition model 166, a recursive battery model 168, and optionally abattery life model 170 and a fuel economy model 172. It should beappreciated that the described one or more models are intended to bemerely illustrative and not limiting.

Based at least in part on the input operational parameters, the one ormore models, and the objective function 165, the control module 32B maydetermine battery parameter setpoints 174 to be implemented. In someembodiments, the battery parameter setpoints 174 may be implemented tode-rate or re-rate the battery system 12. Accordingly, the batteryparameter setpoints 174 may include charge power setpoints 176 and/ordischarge power setpoints 178. For example, the control module 32B mayinstruct the electrical energy generator 42 to implement the chargepower setpoints 176 to control charging current and/or charging voltagesupplied to the lithium ion battery module 28. Additionally, the controlmodule 32B may implement the discharge power setpoints 178 to controlthe discharging current and/or discharging voltage output by the lithiumion battery module 28.

As will be described in more detail below, in an intelligent controlscheme, the control module 32B may determine the battery parametersetpoints 174 taking into account predicted effects implementing thebattery parameter setpoints 174 may have, such as effects on thepredicted temperature trajectory 208, predicted battery life span 266,and predicted battery contribution to fuel economy 288. Morespecifically, the control module 32B may use the one or more models toproject operational parameters of the battery system over a predictionhorizon (e.g., multiple time steps in the future). Additionally, thecontrol module 32B may determine the battery parameter setpoints usingthe objective function 165, which describes a desired balance betweenthe projected effects on the operational parameters, to controloperational parameters of the battery system over a control horizon(e.g., multiple time steps in the future).

As used herein, a “prediction horizon” is intended to describe a periodfor which trajectory of an operational parameter (e.g., driving pattern,battery temperature, or battery current) is predicted. On the otherhand, the control horizon is intended to describe a period for whichtrajectory of a parameter setpoint (e.g., charge current, dischargecurrent, charge voltage, discharge voltage) is determined. In someembodiments, the control horizon may be less than or equal to theprediction horizon.

To help illustrate, one embodiment of a process 180 for determining thebattery parameter setpoints 174 in an intelligent control scheme isdescribed in FIG. 19. Generally, the process 180 includes generatingelectrical energy (process block 182), determining a battery temperature(process block 184), and determining whether the battery temperature isgreater than a temperature threshold (decision block 186). When thebattery temperature is greater than the temperature threshold, theprocess 180 includes disconnecting a lithium ion battery (process block188), capturing electrical energy with a lead-acid battery (processblock 190), supplying power only from the lead-acid battery (processblock 192), and optionally adjusting one or more models (process block193). When the battery temperature is not greater than the temperaturethreshold, the process 180 includes determining a target temperaturetrajectory and/or a temperature threshold (process block 194),determining a predicted battery temperature trajectory (process block198), and determining and implementing battery parameter setpoints(process block 196). In some embodiments, process 180 may be implementedby instructions store in memory 36 and/or another suitable tangible,non-transitory computer-readable medium that are executable by processor34 and/or another suitable processing circuitry.

Accordingly, similar to process block 86, the control module 32B (e.g.,the vehicle control module 62) may instruct the electrical energygenerator 42 to generate electrical energy (process block 182).Additionally, similar to process block 88, the control module 32B (e.g.,battery control module 58) may determine the lithium ion batterytemperature 162 (process block 184).

The control module 32B may then determine whether the lithium ionbattery temperature 162 is greater than a temperature threshold(decision block 186). In some embodiments, the temperature threshold maybe predetermined and stored in memory 36. Thus, the control module 32Bmay retrieve the temperature threshold from memory 36 and compare itwith the lithium ion battery temperature 162.

Similar to process block 118, when the control module 32B determinesthat the battery temperature 162 is greater than the temperaturethreshold, the control module 32B (e.g., battery control module 58) mayinstruct the relay 46 to change to the second state and disconnect thelithium ion battery module 28 (process block 188). Since the lithium ionbattery module 28 is disconnected, the lead-acid battery module 30 maycapture the generated electrical energy (process block 190) and supplyelectrical power by itself (process block 192). As described above, whenthe lithium ion battery module 28 is disconnected, it may ceasecharging/discharging and maintain its state of charge. As such,disconnecting the lithium ion battery module 28 may provide the fastestrate of cooling. However, providing electrical power with only thelead-acid battery module 30 may affect vehicle performance because thelead-acid battery module 30 may power more electrical devices.

In other words, the temperature threshold may be set such that thelithium ion battery module 28 is disconnected only as a last resort. Infact, as will be described in more detail below, using an intelligentcontrol scheme should enable the lithium ion battery temperature 162 tobe consistently maintained below the temperature threshold sinceoperation may be controlled based at least in part on a predictedtrajectory of the lithium ion battery temperature 208. As such, in someembodiments, the temperature threshold in an intelligent control schememay be set at the highest acceptable temperature of the lithium ionbattery module 28. In fact, in some embodiments, the temperaturethreshold in an intelligent control scheme may be greater than or equalto the higher temperature threshold in a reactive control scheme.

Moreover, since an intelligent control scheme enables the batteryparameter setpoints to be adjusted in advance of reaching thetemperature threshold, reaching the temperature threshold may indicatean inaccuracy in the predicted battery temperature trajectory 208. Insome instances, the inaccuracy may result from unanticipatedenvironmental changes that were not accounted for in the one or moremodels used to determine the predicted battery temperature trajectory208. In other instances, the inaccuracies may result from inability forthe one or more models to accurately describe operation of the vehicle10. Thus, when the lithium ion battery temperature 162 repeatedlyreaches the temperature threshold, the control module 32B determine thatinaccuracies are present in the one or more models.

In some embodiments, when inaccuracies are detected, the control module32B may adjust the one or more models to more accurately describeoperation (process block 193). For example, in some embodiments, thecontrol module 32B adjust the one or more models based at least in parton previously implemented battery parameters and the resultingoperational parameters (e.g., battery temperature 162). Additionally oralternatively, the control module 32B may empirically adjust the one ormore models either online or offline. For example, during operation ofthe vehicle 10, the control module 32B may calibrate the one or moremodels online to describe each implemented set of battery parametersetpoints 174 and resulting operational parameters. Additionally, whenthe vehicle 10 is off, the control module 32 may calibrate the one ormore models offline by running a calibration sequence that implementsvarious sets of battery parameter setpoints 174 and determines resultingoperational parameters.

On the other hand, when the lithium ion battery temperature 162 is notgreater than the temperature threshold, the control module 32B maydetermine a target battery temperature trajectory (process block 194).More specifically, the target temperature trajectory and/or thetemperature threshold may serve as constraints on the lithium ionbattery temperature 162. Thus, as will be described in more detailbelow, the target temperature trajectory and/or the temperaturethreshold may be determined to directly influence subsequent controlover operation (e.g., de-rating and/or re-rating) of the battery system12.

Accordingly, based at least in part on the target temperature trajectoryand/or the temperature threshold, the control module 32B may determinethe predicted battery temperature trajectory (process block 196). Thecontrol module 32B may then determine battery parameter setpoints 174and implement the battery parameter setpoints 174 to facilitaterealizing the predicted battery temperature trajectory (process block198). More specifically, the control module 32B may determine thebattery parameter setpoints such that the predicted battery temperaturetrajectory 208 is guided toward the target battery temperaturetrajectory and/or maintained below the battery temperature threshold206. In some embodiments, control module 32B may determine the predictedbattery temperature trajectory 208 using the thermal predictive model164.

To help illustrate, one embodiment of a thermal predictive model 164 isdescribed in FIG. 20. It should be appreciated that the describedthermal predictive model 164 is intended merely to be illustrative andnot limiting. Generally, the thermal predictive model 164 may be a modelthat describes effects operation of the battery system 12 has on thelithium ion battery temperature 162. For example, in the depictedembodiment, the thermal predictive model 164 may predict the temperatureof the lithium ion battery over a prediction horizon (e.g., a predictedtemperature trajectory 208) based on input parameters for a present timestep including the battery temperature 162, a predicted driving pattern202, a predicted battery resistance 204, a target temperature trajectoryand/or temperature threshold 206, and optionally the environmentaltemperature 163. Additionally or alternatively, the thermal predictivemodel 164 may determine the environmental temperature 163 based at leastin part on the other operational parameters.

Additionally, the thermal predictive model 164 may determine batteryparameter setpoints 174 to implement in the battery system 12. Forexample, the thermal predictive model 164 may determine the batteryparameter setpoints 174, which when implemented de-rate and/or re-ratethe battery system 12. Thus, as described above, the battery parametersetpoints 174 may include any combination of a charge current 210, adischarge current 212, a charge voltage 214, and a discharge voltage216.

One embodiment of a process 218 for operating the thermal predictivemodel 164 is described in FIG. 21. Generally, the process 218 includesdetermining relevant temperature(s) (process block 220), determining apredicted driving pattern (process block 222), determining a predictedbattery resistance (process block 224), determining a target temperaturetrajectory/temperature threshold (process block 226), and determining apredicted temperature trajectory (process block 228). In someembodiments, process 218 may be implemented by instructions store inmemory 36 and/or another suitable tangible, non-transitorycomputer-readable medium that are executable by processor 34 and/oranother suitable processing circuitry.

Accordingly, the control module 32B may determine the relevanttemperature(s) (process block 220). In some embodiments, the relevanttemperatures may include the lithium ion battery temperature 162 and/orthe environmental temperature 163. For example, the control module 32Bmay utilize a temperature sensor 60 coupled to the battery system 12 todirectly measure temperature of the lithium ion battery module 28 and atemperature sensor 60 coupled to the vehicle 10 to directly measuretemperature of environment surrounding the vehicle 10. Additionally oralternatively, the control module 32B may utilize other types of sensors60 to measure parameters indicative of the lithium ion batterytemperature 162 and/or the environmental temperature 163. Furthermore,in some embodiments, the control module 32B may either continuously orperiodically determine the relevant temperature(s), for example, basedon a fixed time cycle and/or in response to indication to run thethermal predictive model 164.

The control module 32B may also determine the predicted driving pattern202 of the vehicle 10 (process block 222). More specifically, thepredictive driving pattern 202 may describe how the vehicle 10 isexpected to be driven over a prediction horizon. In some embodiments,the control module 32B may determine the predicted driving pattern 202based at least in part on the previous driving pattern of the vehicle,for example, using the driving pattern recognition model 166.

To help illustrate, one embodiment of a driving pattern recognitionmodel 166 is described in FIG. 22. It should be appreciated that thedescribed driving pattern recognition model 166 is intended merely to beillustrative and not limiting. Generally, the driving patternrecognition model 166 is a model that describes a how a vehicle 10 isexpected to be driven over a prediction horizon (e.g., predicted drivingpattern 202). For example, in the depicted embodiment, the drivingpattern recognition model 166 may determine the predicted drivingpattern 202 based at least in part on the previous driving pattern 232of the vehicle 10, the battery current 158, and the environmentaltemperature 163.

In some embodiments, the predicted driving pattern 202 may be describedas the root-mean-square (RMS) current 234 and/or an average current. Inother words, in such embodiments, the predicted driving pattern 202 isdescribed as static battery current that is expected to be present overthe prediction horizon. As such, the predicted driving pattern 202 maybe determined based on the presently determined battery current 158 andthe previous driving pattern 232, which may include previouslydetermined battery current. Additionally or alternatively, greateramounts of detail may be included in the driving pattern recognitionmodel 166 to enable a dynamic predicted driving pattern 202 over theprediction horizon. For example, the predicted driving pattern 202 maydescribe battery currents that are expected to be present at each pointin time over the prediction horizon.

One embodiment of a process 236 for operating the driving patternrecognition model 166 is described in FIG. 23. Generally, the process236 includes determining an environmental temperature (process block238), determining a battery current (process block 240), determining aprevious driving pattern (process block 242), and determining apredicted vehicle driving pattern (process block 244). In someembodiments, the process 236 may be implemented by instructions store inmemory 36 and/or another suitable tangible, non-transitorycomputer-readable medium that are executable by processor 34 and/oranother suitable processing circuitry.

Accordingly, the control module 32B may determine the environmentaltemperature 163 (process block 238). In some embodiments, the controlmodule 32B may utilize a temperature sensor 60 coupled to vehicle 10 todirectly measure temperature of the surrounding environment.Additionally, the control module 32B may determine the battery current158 (process block 240). In some embodiments, the control module 32B mayutilize a current sensor electrically coupled to the terminal 54 of thelithium ion battery module 28 to measure the battery current 158 (e.g.,current used to charge the lithium ion battery module 28 and currentoutput by the lithium ion battery module 28).

The control module 32B may also determine the previous driving pattern232 of the vehicle 10 (process block 242). As described above, in someembodiments, the driving pattern may be expressed as the expectedbattery current over a prediction horizon. In such embodiments, theprevious driving pattern 232 may include battery currents determined atprevious points in time over the life of the lithium ion battery module28. Additionally, in some embodiments, the previous driving pattern 232may be stored in memory 36 as a curve. Thus, the control module 32B maydetermine the previous driving pattern 232 by retrieving the curve frommemory 36.

Using the driving pattern recognition model 166, the control module 32Bmay then determine the predicted driving pattern 202 (process block244). In the above described embodiment, the control module 32B maydetermine the predicted driving pattern 202 based at least in part onthe battery current 158, the environmental temperature 163, and theprevious driving pattern 232. More specifically, since drivers generallyhave fixed driving habits (e.g., routes, acceleration/brakingtendencies, drive times), it is likely that the predicted drivingpattern 202 may be similar to at least a portion of the previous drivingpattern 232. Moreover, the present operating parameters (e.g., profileof battery current 158 and/or environmental temperature 163) mayfacilitate identifying similar portions of the previous driving pattern232 as well as adjusting portions of the previous driving pattern 232 toaccount from the current operating parameters.

To help illustrate, in some embodiments, the control module 32B maydetermine the predicted driving pattern 202 as a static RMS current thatis expected to occur over a prediction horizon. For example, based atleast in part on the presently determined battery current 158, thecontrol module 32B may identify a portion of the previous drivingpattern 232 that is expected to occur over the prediction horizon. Thecontrol module 32B may then determine the predicted driving pattern 202by determining a square each of the battery currents in the identifiedportion, determining an arithmetic mean of the squared battery currents,and determining a square root of the arithmetic mean. Additionally oralternatively, the control module 32B may determine the predicteddriving pattern 202 by determining a square of each of the batterycurrent in the previous driving pattern 232 and the presently determinedbattery current 158, determining an arithmetic mean of the squaredbattery currents, and determining a square root of the arithmetic mean.

To further illustrate, in some embodiments, the control module 32B maydetermine the predicted driving pattern 202 as a predicted batterycurrent at points in time over the prediction horizon. For example,based at least in part on profile of the presently determined batterycurrent 158, the control module 32B may identify a portion of theprevious driving pattern 232 that is expected to occur over theprediction horizon. The control module 32B may then determine thepredicted driving pattern 202 should be similar to the identifiedportion of the previous driving pattern 232. Accordingly, the controlmodule 32B is the identified portion with any adjustments due to presentoperating conditions, such as environmental temperature 163.

In fact, in some embodiments, additional present operating conditionsmay further facilitate identifying portions of the previous drivingpattern 232. For example, the control module 32B may identify portionsof the previous driving pattern 232 based at least in part on time ofthe day or duration of travel. Additionally, the previous drivingpattern 232 may be updated with the presently determined battery current158 to facilitate determining the predicted driving pattern 202 infuture time steps. For example, in some embodiments, the presentlydetermined battery current 158 may be added to the previous drivingpattern 232 and stored in memory 36 as a curve.

Returning to the process 218 of FIG. 21, the control module 32B may thendetermine the predicted lithium ion battery resistance 204 (processblock 224). Generally, the resistance of the lithium ion battery module28 is dynamic during operation and over the course of its life span. Forexample, the resistance may increase as the lithium ion battery module28 ages and resistance may be inversely related to environmentaltemperature. Additionally, the resistance may pulse (e.g., spike) duringoperation, for example, when the lithium ion battery module 28 ischarged during regenerative braking or discharged during a start-stopoperation. In some embodiments, the control module 32B may utilize therecursive battery model 168 to facilitate determining the predictedlithium ion battery resistance 204.

To help illustrate, one embodiment of a recursive battery model 168 isdescribed in FIG. 24. It should be appreciated that the describedrecursive battery model 168 is intended merely to be illustrative andnot limiting. Generally, the recursive battery model 168 may be a modelthat determines state of health 246 of a battery. In some embodiments,the state of health 246 may include the predicted battery resistance 204of the lithium ion battery module 28 over the prediction horizon and/ora current battery age 250 of the lithium ion battery module 28. Forexample, as will be described in more detail below, the recursivebattery model 168 may facilitate determining a current age 250 of thebattery based at least in part on the presently determined batterytemperature 162 and previously determined battery temperatures 252.Additionally, in the depicted embodiment, the recursive battery model168 may facilitate determining a predicted lithium ion batteryresistance 204 based at least in part on the predicted driving pattern202, the battery current 158, and the bus voltage 160, and a previouslydetermined bus voltage 248.

One embodiment of a process 254 for operating the recursive batterymodel 168 to determine the predicted battery resistance 204 is describedin FIG. 25. Generally, the process 254 includes determining a predicteddriving pattern (process block 256), determining a battery current(process block 258), determining a bus voltage (process block 260),determining a previous bus voltage (process block 262), and determininga predicted battery resistance (process block 264). In some embodiments,the process 254 may be implemented by instructions store in memory 36and/or another suitable tangible, non-transitory computer-readablemedium that are executable by processor 34 and/or another suitableprocessing circuitry.

Accordingly, the control module 32B may determine the predicted drivingpattern 202 (process block 256). In some embodiments, the control module32B may determine the predicted driving pattern 202 using the drivingpattern recognition model 166 as described in process 236. Additionally,the control module 32B may determine the battery current 158 (processblock 258). In some embodiments, the control module 32B may utilize acurrent sensor electrically coupled to the terminal 54 of the lithiumion battery module 28 to measure the battery current 158 (e.g., currentused to charge the lithium ion battery module 28 and current output bythe lithium ion battery module 28). Furthermore, the control module 32Bmay determine the bus voltage 160 (process block 260). In someembodiments, the control module 32B may utilize a voltage sensorelectrically coupled to the bus 26 to measure the bus voltage 160.

The control module 32B may also determine the previous bus voltage 248(process block 262). More specifically, the previous bus voltage 252 mayinclude a bus voltage determined in a previous time step. Accordingly,the previous bus voltage 252 may be stored in memory 36 and the controlmodule 32B may determine the previous bus voltage 248 by retrieving itfrom memory 36. Furthermore, the control module 32B may store thepresently determined bus voltage 160 in memory 36 for use as theprevious bus voltage 248 in the next time step.

Using the recursive battery model 168, the control module 32B may thendetermine the predicted lithium ion battery resistance 204 (processblock 264). In some embodiments, predictive lithium ion batteryresistance 204 may be an RMS resistance value that is expected to occurover a prediction horizon. For example, in the above describedembodiment, the recursive battery model 168 may determine the predictivelithium ion battery resistance 204 based at least in part on thepredicted driving pattern 202, the battery current 158, the bus voltage160, and the previous bus voltages 248. In such embodiments, thepredicted battery resistance may be calculated as follows:

$\begin{matrix}{R = \frac{\Delta\; V*I}{I_{RMS}}} & (1)\end{matrix}$where R is the predicted battery resistance 204, ΔV is the differencebetween the presently determined bus voltage 160 and the previous busvoltage 248, I is the presently determined battery current 158, andI_(RMS) is the predicted driving pattern 202 expressed as an RMScurrent. In this manner, the predicted battery resistance 204 maydetermine the predicted battery resistance 204 with appropriateconsideration of resistance pulses, for example, due to charging duringregenerative braking or discharging during start-stop.

Returning to the process 218 of FIG. 21, the control module 32B may thendetermine a target temperature trajectory and/or a temperature threshold206 (process block 226). In some embodiments, the target temperaturetrajectory and/or temperature threshold 206 may be stored in memory 36.Accordingly, the control module 32B may determine the target temperaturetrajectory and/or temperature threshold 206 by retrieving them frommemory 36.

Additionally, as described above, the control module 32B may controloperation of the battery system 12 based at least in part on the targettemperature trajectory and/or temperature threshold 206. In other words,the control module 32B may determine the target temperature trajectoryand/or temperature threshold 206 based on desired future operation ofthe battery system 12. For example, when lithium ion battery temperature162 is a primary concern, the control module 32B may determine atemperature threshold 206 that describes a temperature, which thepresent and future battery temperatures are desired to be maintainedbelow.

As described above, the lithium ion battery temperature 162 may alsoaffect other factors, such as the life span of the lithium ion batterymodule 28, fuel economy contribution by the lithium ion battery module28, drivability of the vehicle 10, and the like. Accordingly, thecontrol module 32B may determine a target temperature trajectory 206that describes temperatures over a control horizon, which the lithiumion battery temperature 162 is desired to be at. As such, the targettemperature trajectory 206 may be determined to balance the effects onvarious factors expected to occur in future operation.

For example, the control module 32B may determine the target temperaturetrajectory 206 based at least in part on a predicted battery life spanof the lithium ion battery module 28 and/or a predicted fuel economycontribution by the lithium ion battery module 28. In such embodiments,determining the target temperature trajectory 206 may includedetermining a predicted battery life span (process block 229) anddetermining a predicted fuel economy contribution (process block 230).For example, in some embodiments, the control module 32B may determinethe predicted battery life span using the battery life model 170.

To help illustrate, one embodiment of a battery life model 170 isdescribed in FIG. 26. It should be appreciated that the describedbattery life model 170 is intended merely to be illustrative and notlimiting. Generally, the battery life model 170 may be a model used todetermine a predicted battery life span 266 of the lithium ion batterymodule 28. For example, in the depicted embodiment, the battery lifemodel 170 determines the predicted battery life span 266 based at leastin part on a predicted driving pattern 202, a current battery age 250,and a battery life span threshold 267. Additionally, based on thepredicted battery life span 266, the battery life model 170 maydetermine a battery life target temperature trajectory 268, which, aswill be described in more detail below, may be used to determine thetarget temperature trajectory 206 supplied to the thermal predictivemodel 164.

One embodiment of a process 270 for operating the battery life model 170is described in FIG. 27. Generally the process 270 includes determininga predicted driving pattern (process block 272), determining a batterylife span threshold (process block 274), determining a current batteryage (process block 275), determining a predicted battery life span(process block 276), and determining a battery life target temperaturetrajectory (process block 278). In some embodiments, the process 270 maybe implemented by instructions store in memory 36 and/or anothersuitable tangible, non-transitory computer-readable medium that areexecutable by processor 34 and/or another suitable processing circuitry.

Accordingly, the control module 32B may determine the predicted drivingpattern 202 (process block 272). In some embodiments, the control module32B may determine the predicted driving pattern 202 using the drivingpattern recognition model 166 as described in process 236. For example,the control module 32B may retrieve the predicted driving pattern 202from memory 36.

Additionally, the control module 32B may also determine a battery lifespan threshold 267 (process block 274). More specifically, the batterylife span threshold 267 may describe duration the lithium ion batterymodule 28 is expected to last. For example, in some embodiments, thebattery life span threshold 267 may be eight years and/or a specificnumber of charging/discharging cycles. Additionally, in someembodiments, the battery life span threshold 267 may be predeterminedand stored in memory 36. Accordingly, the control module 32B maydetermine the battery life span threshold 267 by retrieving it frommemory 36.

The control module 32B may also determine the current battery age 250 ofthe lithium ion battery module 28 (process block 275). As describedabove, the current battery age 250 may be determined using the recursivebattery model 168. One cause of aging may be result of charging anddischarging the lithium ion battery module 28 (e.g., cycle aging).Accordingly, the recursive battery model 168 may determine the currentbattery age 250 based at least in part on number of charging/dischargingcycles previous performed. In some embodiments, the control module 32Bmay determine when the lithium ion battery 28 is charging and when thelithium ion battery 28 is discharging may be determined based on thebattery currents 158 and/or the bus voltage 160. As such, the recursivebattery model 168 may indicate the current cycle age of the lithium ionbattery 28 based at least in part on the battery current 158 and/or thebus voltage 160.

Another cause of aging may be the result of battery temperature (e.g.,calendar aging). Accordingly, the recursive battery model 168 may alsodetermine the current battery age 250 based at least in part on thetemperature experienced by the lithium ion battery 28 over its lifetime.Accordingly, the recursive battery model 168 may indicate the currentcalendar age of the lithium ion battery 28 based at least in part on thebattery temperature 162 and/or previous battery temperatures 252.

One embodiment of a process 280 for operating the recursive batterymodel 168 to determine the current battery age 250 (e.g., calendar age)is described in FIG. 28. Generally, the process 280 includes determininga battery temperature (process block 282), determining previous batterytemperatures (process block 284), and determining a current battery age(process block 286). In some embodiments, the process 280 may beimplemented by instructions store in memory 36 and/or another suitabletangible, non-transitory computer-readable medium that are executable byprocessor 34 and/or another suitable processing circuitry.

Accordingly, the control module 32B may determine the lithium ionbattery temperature 162 (process block 282). In some embodiments, thecontrol module 32B may utilize a temperature sensor 60 coupled to thebattery system 12 to directly measure temperature of the lithium ionbattery module 28. In other embodiments, the control module 32B mayutilize other types of sensors 60 to measure parameters indicative ofthe lithium ion battery temperature 162.

Additionally, the control module 32B may determine previous batterytemperatures 252 (process block 284). In some embodiments, the previousbattery temperatures 252 may include a portion or all of the batterytemperatures previously measured during life of the lithium ion batterymodule 28. Additionally, in some embodiments, the previous batterytemperatures 252 may be stored in memory 36. Accordingly, the controlmodule 32B may determine the previous bus voltages 248 by retrievingthem from memory 36. Furthermore, the control module 32B may store thepresently determined lithium ion battery temperature 162 in memory 36 aspart of the previous battery temperatures 252 to facilitate determiningbattery age in future time steps.

Using the recursive battery model 168, the control module 32B maydetermine the current battery age 250 (process block 286). Morespecifically, the control module 32B may determine how much of the totallife of the lithium ion battery module 28 has been exhausted. Forexample, in the described example, the recursive battery model 168 maydescribe a relationship between the portion the battery life spanalready exhausted and magnitude and/or duration of the past and presentbattery temperatures (e.g., battery temperature 162 and the previousbattery temperatures 252). In some embodiments, the current battery age250 may be expressed in years, for example, based on the battery lifespan threshold 267 multiplied by the exhausted percentage.

Returning to the process 270 of FIG. 27, the control module 32B may thendetermine the predicted battery life span 266 of the lithium ion battery28 using the battery life model 170 (process block 276). Morespecifically, the predicted battery life span 266 may include a sum ofthe current battery age 250 and the predicted remaining battery lifespan. In the above described embodiment, the battery life model 170 maydetermine the predicted battery life span 266 based at least in part onthe predicted driving pattern 202 and the current battery age 250 (e.g.,calendar age and/or cycle age).

As described above, calendar aging may be caused by lithium ion batterytemperature 162. Accordingly, to determine the predicted battery lifespan due to calendar aging, the battery life model 170 may determine thelithium ion battery temperatures expected to occur over future operationbased at least in part on the predicted driving pattern 202. Morespecifically, as described above, the predicted driving pattern 202 maydescribe battery currents expected over a future prediction horizon. Assuch, the expected lithium ion battery temperatures may be determinedbased at least in part on the expected battery currents. The batterylife model 170 may then determine the predicted remaining calendar lifespan based on how the expected temperatures will affect life of thelithium ion battery module 28.

Additionally, as described above, cycle aging may be caused bycharging/discharging the lithium ion battery module 28. In someembodiments, when the lithium ion battery module 28 is charging and whenthe lithium ion battery module 28 is discharging may be determined basedon its battery current. For example, as described in FIG. 17C, apositive battery current may indicate that the lithium ion batterymodule 28 is charging and a negative battery current may indicate thatthe lithium ion battery module 28 is discharging. Additionally, byintegrating the battery current, an energy throughput projection may bedetermined which may provide a further indication to the predictedremaining cycle life span because the storage capacity may decrease andthe cell resistance may increase as the lithium ion battery 28 ages.

Accordingly, since the predicted driving pattern 202 may describebattery currents expected over a future prediction horizon, the batterylife model 170 determine the predicted battery life span due to cycleaging based at least in part on the predicted driving pattern 202. Thebattery life model 170 may then determine the predicted remaining cyclelife span based on the number of charging/discharging cycles expected inthe future prediction horizon and/or the projected energy throughput.

In this manner, the control module 32B may determine the predictedremaining life span (e.g., predicted remaining calendar life span and/orthe predicted remaining cycle life span) of the lithium ion battery 28.In some embodiments, the predicted remaining calendar life span and thepredicted remaining cycle life span may be combined into a singlepredicted remaining life span, for example, by averaging the two ortaking the lesser of the two. The control module 32B may then determinethe predicted battery life span 266 of the lithium ion battery 28 bysumming together the current battery age 250 and the predicted remaininglife span.

Additionally, the control module 32B may determine the battery lifetarget temperature trajectory 268 based at least in part on thepredicted battery life span 266 and the battery life span threshold 267(process block 278). More specifically, the control module 32B maycompare the two to determine whether the predicted battery life span 266is less than, equal to, or greater than the battery life span threshold267. The control module 32B may then determine the battery lifetemperature trajectory 268 based at least in part on the comparison toadjust the predicted battery life span 266. For example, when thepredicted battery life span 266 is less than the battery life spanthreshold 267, the control module 32B may determine the battery lifetarget temperature trajectory 268 to reduce future battery temperatures.On the other hand, when the predicted battery life span 266 is greaterthan the battery life span threshold 267, the control module 32B maydetermine the battery life target temperature trajectory 268 to enableincreased battery temperatures, which may facilitate improving batteryfuel economy contribution.

In addition to the life span, the control module 32B may controloperation of the battery system 12 based at least in part on fueleconomy contribution by the lithium ion battery module 28. For example,the lithium ion battery module 28 may affect fuel economy by capturingelectrical power during regenerative braking and supplying electricalpower during start-stop, thereby reducing use of the alternator 18 andimproving fuel economy. In some embodiments, the control module 32B maydetermine the predicted battery fuel economy contribution using the fueleconomy model 172.

To help illustrate, one embodiment of a fuel economy model 172 isdescribed in FIG. 29. It should be appreciated that the described fueleconomy model 172 is intended merely to be illustrative and notlimiting. Generally, the fuel economy model 172 may be a model thatdescribes expected contribution by a lithium ion battery module 28 tofuel economy of the vehicle 10 over a prediction horizon (e.g.,predicted battery fuel economy contribution 288). For example, in thedepicted embodiment, the fuel economy model 172 determines the predictedbattery fuel economy contribution 288 based at least in part on apredicted driving pattern 202, a battery current 158, and a battery fueleconomy contribution threshold 290. Additionally, based on the predictedfuel economy contribution 288, the fuel economy model 172 may determinea fuel economy target temperature trajectory 292, which, as will bedescribed in more detail below, may be used to determine the targettemperature trajectory 206 supplied to the thermal predictive model 164.

One embodiment of a process 294 for operating the fuel economy model 172is described in FIG. 30. Generally, the process 294 includes determininga predicted driving pattern (process block 296), determining a batterycurrent (process block 298), determining a battery fuel economycontribution threshold (process block 300), determining a battery fueleconomy contribution (process block 302), and determining a fuel economytarget temperature trajectory (process block 304). In some embodiments,the process 294 may be implemented by instructions store in memory 36and/or another suitable tangible, non-transitory computer-readablemedium that are executable by processor 34 and/or another suitableprocessing circuitry.

Accordingly, the control module 32B may determine the predicted drivingpattern 202 (process block 296). In some embodiments, the control module32B may determine the predicted driving pattern 202 using the drivingpattern recognition model 166 as described in process 236. Additionally,the control module 32B may determine the battery current 158 (processblock 298). In some embodiments, the control module 32B may utilize acurrent sensor electrically coupled to the terminal 54 of the lithiumion battery module 28 to measure the battery current 158 (e.g., currentused to charge the lithium ion battery module 28 and current output bythe lithium ion battery module 28).

Furthermore, the control module 32B may determine the battery fueleconomy contribution threshold 290 (process block 300). Generally, thebattery fuel economy contribution threshold 290 may describe a thresholdamount desired for the lithium ion battery module 28 to contribute(e.g., improve) to fuel economy of the vehicle 10. Accordingly, in someembodiments, the battery fuel economy contribution threshold 290 may bepredetermined by a manufacturer of the vehicle 10 and/or the batterysystem 12 and stored in memory 36. Thus, the control module 32B maydetermine the battery fuel economy contribution threshold by retrievingit from memory 36.

Using the fuel economy model 172, the control module 32B may thendetermine the predicted battery fuel economy contribution 288 (processblock 302). More specifically, the predicted battery fuel economycontribution 288 may describe the effect on fuel economy of the vehicle10 caused by the lithium ion battery module 28 over the predictionhorizon. In some embodiments, the predicted battery fuel economycontribution 288 may describe benefits to fuel economy caused by use ofthe lithium ion battery module 28 and detriments to fuel economy causedby reduced use of the lithium ion battery module 28 (e.g., de-rating).For example, the predicted battery fuel economy contribution 288 mayaccount for when the lithium ion battery module 28 is expected tocapture electrical power during regenerative braking and supplyelectrical power to the electrical system 44, thereby reducing use ofthe alternator 18 and improving fuel economy.

In the above described embodiment, the fuel economy model 172 maydetermine the predicted battery fuel economy contribution 288 based atleast in part on the predicted driving pattern 202, the battery current158, and the battery fuel economy contribution threshold 290. Asdescribed above, the battery current 158 and the predicted drivingpattern 202 may describe expected battery current over the predictionhorizon. More specifically, patterns in the expected battery current mayindicate operations performed by the lithium ion battery module 28. Forexample, a current discharge pulse may indicate cranking the internalcombustion engine 24 during a start-stop operation. Additionally, acurrent charge pulse may indicate that the lithium ion battery module 28is capturing electrical energy during regenerative braking. In thismanner, the control module 32B may determine when and/or duration thelithium ion battery module 28 is expected to perform an operation (e.g.,start-stop) that affects fuel economy of the vehicle 10 during theprediction horizon.

Based at least in part on the predicted battery fuel economycontribution 288 and the battery fuel economy contribution threshold290, the control module 32B may determine the fuel economy targettemperature trajectory 292 (process block 302). More specifically, thecontrol module 32B may compare the two to determine whether thepredicted battery fuel economy contribution 288 is less than, equal to,or greater than the battery fuel economy contribution threshold 290. Thecontrol module 32B may then determine the fuel economy targettemperature trajectory 292 based at least in part on the comparison toadjust the predicted battery fuel economy contribution 288. For example,when the predicted battery fuel economy contribution 288 is less thanthe battery fuel economy contribution threshold 290, the control module32B may determine the fuel economy target temperature trajectory 292 toenable increased lithium ion battery temperatures and, thus, increasedlithium ion battery module 28 operation. On the other hand, when thepredicted battery fuel economy contribution 288 is greater than thepredicted battery fuel economy contribution threshold 290, the controlmodule 32B may determine the fuel economy target temperature trajectory292 to enable reduced battery temperatures, which may facilitateimproving battery life span.

Returning to the process 218 of FIG. 21, as described above, the controlmodule 32B may determine the target temperature trajectory 206accounting for various factors, such as battery life span of the lithiumion battery module 28 and/or fuel economy contribution by the lithiumion battery module 28. Accordingly, in some embodiments, the controlmodule 32B may determine the target temperature trajectory 206 based atleast in part on the battery life target temperature trajectory 268and/or the fuel economy target temperature trajectory 292 (e.g., factortarget temperature trajectories).

However, in some instances, various factors may be inversely related.For example, fuel economy contribution may be increased by increasingcharging/discharging of the lithium ion battery module 28. However, theincreased charging/discharging may also result in increased batterytemperature, which decreases life span of the lithium ion battery module28. Accordingly, the control module 32B may utilize the objectivefunction 165 to provide a weighting between the various factors. Forexample, the objective function 165 may enable placing greater emphasisbattery life span over battery fuel economy contribution. Accordingly,in such an embodiment, the battery life target temperature trajectory268 may be weighted more heavily than the fuel economy targettemperature trajectory 292 when determining the target temperaturetrajectory 206.

In fact, in some embodiments, the objective function 165 may enabledynamically changing the weightings between the factors. For example, auser (e.g., driver or mechanic) may manually change the weightings basedon personal importance. Additionally or alternatively, the weightingsmay be adjusted automatically by placing a greater emphasis on a factorwhen the factor falls below and/or approaches a threshold. For example,a greater emphasis may be placed on lithium ion battery temperature 162the closer the lithium ion battery temperature 162 is to the temperaturethreshold. Accordingly, in such embodiments, the temperature thresholdmay be weighted more heavily than the battery life target temperaturetrajectory 268 and the fuel economy target temperature trajectory 292when determining the target temperature trajectory 206.

Based on the target temperature trajectory and/or the temperaturethreshold 206, the control module 32B may determine the predictedtemperature trajectory 208 (process block 228). More specifically, thepredicted temperature trajectory 208 may be determined such that thepredicted temperature trajectory 208 is guided toward the targettemperature trajectory. Additionally or alternatively, the predictedtemperature trajectory 208 may be determined such that the predictedtemperature trajectory is maintained below the temperature threshold.

Returning to process 180 of FIG. 19, the control module 32B maydetermine battery parameter setpoints 174 and implement the batteryparameter setpoints 174 to realize the predicted temperature trajectory208 (process block 198). As described above, in some embodiments, thecontrol module 32B may instruct the battery system 12 to implement thebattery parameter setpoints 174 to de-rate and/or re-rate the batterysystem 12, thereby controlling the lithium ion battery temperature 162.

For example, the control module 32B may instruct the electrical energygenerator 42 to reduce generated charge current 210 and/or chargevoltage 214 to de-rate the battery system 12, thereby reducing lithiumion battery temperature 162. Additionally, the control module 32B mayinstruct the electrical energy generator 42 to increase generated chargecurrent 210 and/or charge voltage 214 to re-rate the battery system 12,thereby increasing operation of the lithium ion battery module 28.Furthermore, the control module 32B may instruct the battery system 12to reduce discharge current 212 and/or discharge voltage 216 output bythe lithium ion battery module 28 to de-rate the battery system 12.

As such, the intelligent control scheme described above may facilitatecontrolling temperature of the lithium ion battery module 28 based atleast in part on presently determined operational parameters (e.g.,lithium ion battery temperature 162) and a temperature threshold as wellas predicted operational parameters over a prediction horizon and atarget temperature trajectory. For example, using the target temperaturetrajectory 206 may facilitate de-rating/re-rating techniques topreemptively cool a lithium ion battery module 28 based at least in parton whether the predicted trajectory of the operational parameters areexpected to approach or surpass respective thresholds.

To help illustrate, results from testing a vehicle with an intelligentde-rating scheme is described below. More specifically, the vehicle wasdriven in one New European Drive Cycle (NEDC). The NEDC is described indescribed in FIG. 31A. More specifically, FIG. 31A is a plot thatdescribes the speed of the vehicle during the NEDC with a drive cyclecurve 306, in which time in seconds is shown on the X-axis and speed ofthe vehicle is shown on the Y-axis.

As described by the drive cycle curve 306, the vehicle was driventhrough an urban drive cycle four times between second 0 to second 780.More specifically, during each urban drive cycle, the vehicle startedidle. After remaining idle for 11 seconds, the vehicle accelerated toapproximately 5 m/s in 4 seconds, cruised for 8 seconds, and deceleratedcoming to a stop in 5 seconds. After remaining idle for 21 seconds, thevehicle accelerated to approximately 10 m/s in 12 seconds, cruised for24 seconds, and decelerated coming to a stop in 11 seconds. Afterremaining idle for another 21 seconds, the vehicle accelerated toapproximately 15 m/s in 26 seconds, cruised for 12 seconds, deceleratedto approximately 10 m/s in 8 seconds, cruised for another 13 seconds,and decelerated coming to a stop in 12 seconds.

Additionally, as described by the drive cycle curve 306, the vehicle wasdriven through an extra-urban drive cycle between second 780 and second1180. More specifically, the vehicle started the extra-urban drive cycleidle. After remaining idle for 20 seconds, the vehicle accelerated toapproximately 20 m/s in 41 seconds, cruised for 50 seconds, deceleratedto approximately 15 m/s in 8 seconds. After cruising at 8 m/s for 69seconds, the vehicle again accelerated to approximately 20 m/s in 13seconds, cruised at 20 m/s for 50 seconds, and accelerated toapproximately 30 m/s in 30 seconds. After cruising at 30 m/s for 30seconds, the vehicle accelerated to approximately 35 m/s in 20 seconds,cruised at 35 m/s for 10 seconds, decelerated to a stop in 34 seconds,and idled for 20 seconds.

During the NEDC, the lithium ion battery module 28 captured electricalenergy when the vehicle decelerated. Additionally, the lithium ionbattery module 28 supplied electrical power to the vehicle's electricalsystem and to the ignition to restart the internal combustion engineduring a start-stop operation. To help illustrate, the battery currentof the lithium ion battery measured during the NEDC is described in FIG.31B. More specifically, FIG. 31B is a plot that describes the batterycurrent with a current curve 308, in which time in seconds is shown onthe X-axis and the battery current is shown on the Y-axis. Morespecifically, a positive battery current indicates that the lithium ionbattery was charging and a negative battery current indicates that thelithium ion battery was discharging.

As described by the current curve 308, during each urban drive cycle,the lithium ion battery supplied a pulse of discharge current to crankthe internal combustion engine at second 11 and captured charge currentdue to regenerative braking between second 23 and second 28.Additionally, the lithium ion battery module 28 supplied a pulse ofdischarge current to crank the internal combustion engine at second 49and captured charge current due to regenerative braking from second 75to second 86. Furthermore, the lithium ion battery supplied a pulse ofdischarge current to crank the internal combustion engine 24 at second107, captured charge current due to regenerative braking from second 145to second 153 and from second 166 to second 188.

Additionally, as described by the current curve 308, the battery currentwas approximately the same during each urban drive cycle. Accordingly,as the vehicle began each drive cycle, the control module 32B in thevehicle was able to determine the predicted driving pattern 202 of thevehicle. For example, determining that the vehicle remained idle fromsecond 195 to second 206, accelerated to approximately 5 m/s from second206 to second 210, and cruised at 5 m/s from second 210 to second 218based on the battery current, the control module 32B was able todetermine the predicted driving pattern 202. More specifically, thecontrol module 32B determined at second 218 a predicted driving pattern202 such that the vehicle was expected to decelerate to a stop fromsecond 218 to second 223, remain idle from second 223 to second 244 andaccelerate to approximately 10 m/s from second 244 to second 256.

In this manner, the vehicle was able to implement battery parametersetpoints 174 based at least in part on the predicted driving pattern202. For example, at second 218, the vehicle was able to determine thepredicted temperature trajectory 208, the predicted battery resistance204, and the predicted battery fuel economy contribution 288 for atleast from second 218 to second 256. In this manner, the vehicle wasable to preemptively de-rate and re-rate the battery system 12 whendesired.

In other words, the techniques described herein may supplement coolingcomponents, such as vent system 66 and thermal system 68, in the batterysystem 12. In fact, the techniques may enable a vehicle to rely solelyon a passive thermal system with passive cooling components, such ascooling fins 74, without the use of additional active coolingcomponents, such as a fan or an evaporator plate.

Thus, one or more of the disclosed embodiments, alone or on combination,may provide one or more technical effects including improvingperformance of a battery system. In particular, the disclosedembodiments may de-rate/re-rate the battery system to regulatetemperature of a lithium ion battery in the battery system, for example,based on fuel economy contribution by the lithium ion battery, life spanof the lithium ion battery, and/or charge capture efficiency of thebattery system. For instance, a control module may utilize a reactivecontrol scheme to de-rate the battery system to reduce operation of thelithium ion battery when temperature of lithium ion battery reaches atemperature threshold. Additionally or alternatively, a control modulemay utilize an intelligent control scheme to de-rate the battery systembased at least in part on a predicted trajectory of temperature of thelithium ion battery. In this manner, the techniques described hereinenable controlling operation of the battery system based at least inpart on various performance factors. The technical effects and technicalproblems in the specification are exemplary and are not limiting. Itshould be noted that the embodiments described in the specification mayhave other technical effects and can solve other technical problems.

The specific embodiments described above have been shown by way ofexample, and it should be understood that these embodiments may besusceptible to various modifications and alternative forms. It should befurther understood that the claims are not intended to be limited to theparticular forms disclosed, but rather to cover all modifications,equivalents, and alternatives falling within the spirit and scope ofthis disclosure.

The invention claimed is:
 1. A tangible, non-transitory,computer-readable medium storing instructions executable by one or moreprocessors of an electrical device, wherein the instructions compriseinstructions to: determine, using the one or more processors, apredicted driving pattern of an automotive vehicle in which a batterymodule is to be deployed; predict, using the one or more processors,operational parameters of the battery module expected to occur when theautomotive vehicle performs the predicted driving pattern based at leastin part on a control scheme implemented by the automotive vehicle;determine, using the one or more processors, a predicted life span ofthe battery module based at least in part on a battery life model thatdescribes a relationship between a predicted remaining life span of thebattery module and the operational parameters of the battery moduleexpected to occur when the automotive vehicle performs the predicteddriving pattern; determine, using the one or more processors, a batterylife span threshold associated with the automotive vehicle; andindicate, using the one or more processors, that the battery module issuitable to be deployed in the automotive vehicle when the predictedlife span of the battery module is greater than or equal to the batterylife span threshold associated with the automotive vehicle; furthercomprising: (a) instructions to control, using the one or processors,operation of the automotive vehicle in accordance with the controlscheme after the battery module is deployed in the automotive vehicle tofacilitate maintaining actual life span of the battery module greaterthan or equal to the battery life span threshold associated with theautomotive vehicle and wherein the instructions to control operation ofthe automotive vehicle in accordance with the control scheme compriseinstructions to: instruct, using the one or more processors, anelectrical generator implemented in an electrical system of theautomotive vehicle to adjust voltage, current, or both of electricalpower output from the electrical generator; instruct, using the one ormore processors, a relay electrically coupled between battery cells ofthe battery module and the electrical system to switch to, maintain, orboth a closed position; instruct, using the one or more processors, therelay electrically coupled between the battery cells of the batterymodule and the electrical system to switch to, maintain, or both an openposition; or any combination thereof; or (b) determine, using the one ormore processors, a current age of the battery module based at least inpart on a recursive battery model that describes a relationship betweenthe current age of the battery module and previous operationalparameters of the battery module; and determine, using the one or moreprocessors, the predicted life span of the battery module based at leastin part on the current age of the battery module and the predictedremaining life span of the battery module; or (c) wherein: theinstructions to determine the predicted driving pattern compriseinstructions to receive the predicted driving pattern from amanufacturer of the automotive vehicle; the instructions to determinethe battery life span threshold comprise instructions to receive thebattery life span threshold from the manufacturer of the automotivevehicle; or both.
 2. A tangible, non-transitory, computer-readablemedium storing instructions executable by one or more processors of anelectrical device, wherein the instructions comprise instructions to:determine, using the one or more processors, a predicted driving patternof an automotive vehicle in which a battery module is to be deployed;predict, using the one or more processors, operational parameters of thebattery module expected to occur when the automotive vehicle performsthe predicted driving pattern based at least in part on a control schemeimplemented by the automotive vehicle; determine, using the one or moreprocessors, a predicted life span of the battery module based at leastin part on a battery life model that describes a relationship between apredicted remaining life span of the battery module and the operationalparameters of the battery module expected to occur when the automotivevehicle performs the predicted driving pattern; determine, using the oneor more processors, a battery life span threshold associated with theautomotive vehicle; and indicate, using the one or more processors, thatthe battery module is suitable to be deployed in the automotive vehiclewhen the predicted life span of the battery module is greater than orequal to the battery life span threshold associated with the automotivevehicle wherein: the instructions to predict the operational parametersof the battery module comprise instructions to predict battery currentexpected to flow through the battery module when the automotive vehicleperforms the predicted driving pattern; and the instructions todetermine the predicted life span of the battery module compriseinstructions to determine the predicted remaining life span of thebattery module based at least in part on the battery current expected toflow through the battery module when the automotive vehicle performs thepredicted driving pattern.
 3. The tangible, non-transitory,computer-readable medium of claim 2, wherein: the instructions topredict the operational parameters of the battery module compriseinstructions to determine a predicted trajectory of temperature of thebattery module based at least in part on the battery current expected toflow through the battery module when the automotive vehicle performs thepredicted driving pattern; and the instructions to determine thepredicted life span of the battery module comprise instructions todetermine the predicted remaining life span of the battery module basedat least in part on the predicted trajectory of the temperature of thebattery module.
 4. A method of testing a battery module, comprising:determining, using processing circuitry, a predicted driving pattern ofan automotive vehicle in which a battery module is to be deployed;predicting, using the processing circuitry, operational parameters ofthe battery module expected to occur when the automotive vehicleperforms the predicted driving pattern based at least in part on acontrol scheme implemented by the automotive vehicle; determining, usingthe processing circuitry, a predicted fuel economy contribution of thebattery module based at least on a fuel economy model that describes arelationship between the predicted fuel economy contribution of thebattery module and the operational parameters of the battery moduleexpected to occur when the automotive vehicle performs the predicteddriving pattern; determining, using the processing circuitry, a fueleconomy contribution threshold associated with the automotive vehicle;and indicating, using the processing circuitry, that the battery moduleis suitable to be deployed in the automotive vehicle when the predictedfuel economy contribution of the battery module is greater than or equalto the fuel economy contribution threshold associated with theautomotive vehicle; further comprising: (a) controlling, using theprocessing circuitry, operation of the automotive vehicle in accordancewith the control scheme after the battery module is deployed in theautomotive vehicle to facilitate maintaining actual fuel economycontribution of the battery module greater than or equal to the fueleconomy contribution threshold associated with the automotive vehicle;and wherein controlling operation of the automotive vehicle inaccordance with the control scheme comprises: instructing, using theprocessing circuitry, an electrical generator implemented in anelectrical system of the automotive vehicle to adjust voltage, current,or both of electrical power output from the electrical generator;instructing, using the processing circuitry, a relay electricallycoupled between battery cells of the battery module and the electricalsystem to switch to, maintain, or both a closed position; instructing,using the processing circuitry, the relay electrically coupled betweenthe battery cells of the battery module and the electrical system toswitch to, maintain, or both an open position; or any combinationthereof; or (b) predicting the operational parameters of the batterymodule comprises predicting battery current expected to flow through thebattery module when the automotive vehicle performs the predicteddriving pattern; and  determining the predicted fuel economycontribution of the battery module comprise determining the predictedfuel economy contribution of the battery module based at least in parton the battery current expected to flow through the battery module whenthe automotive vehicle performs the predicted driving pattern; or (c)determining the predicted driving pattern comprises receiving thepredicted driving pattern of the automotive vehicle from a manufacturerof the automotive vehicle;  determining the fuel economy contributionthreshold comprises to receiving the fuel economy contribution thresholdfrom the manufacturer of the automotive vehicle; or  both.